Medicine – Gonorrhoea: Aetiology, Transmission, Pathogenesis, Clinical Features, Diagnosis, Complications and Treatment

1. Introduction to Gonorrhoea

Gonorrhoea is a common sexually transmitted infection (STI) caused by Neisseria gonorrhoeae, a Gram-negative diplococcus that primarily infects mucosal surfaces of the genitourinary tract, rectum, pharynx and conjunctiva.

It is an important cause of urethritis in men and cervicitis and pelvic inflammatory disease (PID) in women.

The classical presentation in men is purulent urethral discharge accompanied by dysuria, urethral irritation and discomfort.

In women, gonorrhoea frequently produces mild or no symptoms, allowing infection to persist and potentially ascend into the upper genital tract.

Untreated infection may cause epididymitis, pelvic inflammatory disease, infertility, ectopic pregnancy and, occasionally, disseminated gonococcal infection.

An important modern concern is the development of antimicrobial resistance. Gonorrhoea was historically treated with penicillin, tetracyclines and fluoroquinolones, but resistance has made these drugs unsuitable for routine empirical treatment in many regions.

Ceftriaxone, a third-generation cephalosporin, is the principal recommended treatment for uncomplicated gonorrhoea in current major guidelines.

Aetiology and Microbiology

2. Aetiological Agent – Neisseria gonorrhoeae

Gonorrhoea is caused by Neisseria gonorrhoeae, also known as the gonococcus.

It is a Gram-negative, kidney-shaped diplococcus belonging to the genus Neisseria.

The bacteria commonly occur in pairs, with their adjacent surfaces appearing flattened or concave.

This produces the characteristic coffee-bean or kidney-bean appearance on microscopy.

Neisseria gonorrhoeae is a human-adapted pathogen that preferentially infects non-keratinised mucosal epithelium.

Important sites of infection include the urethra, endocervix, rectum, pharynx and conjunctiva.

3. Morphological Characteristics

Neisseria gonorrhoeae is a Gram-negative diplococcus.

On Gram staining, the organisms appear pink or red because they possess a thin peptidoglycan layer and an outer membrane.

In symptomatic male urethritis, the organisms may be seen inside polymorphonuclear neutrophils.

The characteristic microscopic finding is therefore intracellular Gram-negative diplococci within neutrophils.

This finding is highly suggestive of gonorrhoea when observed in a urethral smear from a symptomatic man.

However, Gram staining is less reliable for cervical, rectal and pharyngeal specimens.

4. Important Microbiological Properties

Neisseria gonorrhoeae is oxidase-positive and catalase-positive.

It is a fastidious organism that requires appropriate laboratory conditions for cultivation.

It grows on enriched media, including chocolate agar.

Selective media, such as modified Thayer–Martin medium, may be used to isolate the organism from specimens containing mixed bacterial flora.

A classical laboratory distinction is that N. gonorrhoeae utilises glucose but not maltose.

By comparison, Neisseria meningitidis classically utilises both glucose and maltose.

These biochemical properties are useful traditional microbiology associations, although modern laboratories often use molecular or automated identification methods.

5. Virulence Factors

Neisseria gonorrhoeae possesses several virulence factors that allow it to adhere to mucosal surfaces, evade host immune responses and produce inflammation.

Important virulence factors include type IV pili, opacity-associated proteins, lipooligosaccharide and IgA protease.

These factors contribute to colonisation, epithelial invasion and inflammatory tissue injury.

The organism also demonstrates substantial antigenic variation, particularly involving surface structures.

This helps explain why previous infection does not provide reliable long-term protective immunity.

6. Type IV Pili

Type IV pili are hair-like surface structures that facilitate attachment to epithelial cells.

They help the organism establish infection on mucosal surfaces.

Pili also contribute to bacterial movement and interactions with host cells.

Variation in pilus-associated antigens allows the organism to evade existing immune responses.

This antigenic variation contributes to repeated infection.

7. Opacity-Associated Proteins

Opacity-associated proteins, commonly called Opa proteins, facilitate close interactions between gonococci and host cells.

They contribute to bacterial adherence and invasion.

Variation in Opa protein expression can alter the organism’s interaction with host tissues and immune cells.

This is another mechanism by which N. gonorrhoeae can adapt during infection.

8. Lipooligosaccharide

The outer membrane of Neisseria gonorrhoeae contains lipooligosaccharide (LOS).

LOS has endotoxin-like activity and contributes to the inflammatory response.

It stimulates immune cells and promotes the recruitment of neutrophils.

This inflammatory response is responsible for many clinical manifestations, including purulent urethral discharge.

LOS also contributes to tissue injury during infection.

9. IgA Protease

Neisseria gonorrhoeae produces IgA protease, an enzyme that can cleave certain immunoglobulin A molecules.

IgA is an important component of mucosal immunity.

By interfering with mucosal antibody function, the organism may enhance its ability to colonise epithelial surfaces.

However, gonococcal immune evasion involves multiple mechanisms, not IgA protease alone.

Transmission of Gonorrhoea

10. Sexual Transmission

Gonorrhoea is transmitted predominantly through sexual contact.

Transmission may occur during vaginal, anal or oral intercourse.

The organism spreads through contact with infected genital, rectal or pharyngeal secretions and mucosal surfaces.

Penetrative intercourse is not always necessary for transmission.

An infected individual may transmit gonorrhoea even when no symptoms are present.

This is important because a substantial proportion of infections, particularly cervical and pharyngeal infections, are asymptomatic.

11. Transmission During Vaginal Intercourse

Vaginal intercourse can transmit Neisseria gonorrhoeae between sexual partners.

In men, infection commonly involves the urethra.

In women, the organism preferentially infects the endocervical columnar epithelium.

Infection may also involve the urethra and other genital structures.

Untreated cervical infection can ascend into the uterus and fallopian tubes, causing pelvic inflammatory disease.

12. Transmission During Anal Intercourse

Anal intercourse may transmit gonorrhoea to the rectal mucosa.

Rectal gonorrhoea is frequently asymptomatic.

When symptoms occur, patients may experience rectal discomfort, discharge, bleeding or pain during defecation.

Rectal infection may occur alongside genital or pharyngeal infection.

Testing should therefore consider the anatomical sites of sexual exposure.

13. Transmission During Oral Intercourse

Oral intercourse can transmit gonorrhoea to the pharynx.

Pharyngeal gonorrhoea is commonly asymptomatic.

Some patients experience sore throat or pharyngeal discomfort.

Pharyngeal infection is clinically important because it can contribute to ongoing transmission and may be more difficult to eradicate than uncomplicated urogenital infection.

Appropriate site-specific testing is therefore important.

14. Vertical Transmission

Gonorrhoea can be transmitted from an infected mother to her infant during childbirth.

Exposure to infected genital secretions may result in neonatal conjunctival infection.

This condition is called gonococcal ophthalmia neonatorum.

It can cause severe purulent conjunctivitis and rapid corneal damage.

Without prompt treatment, neonatal gonococcal conjunctivitis may result in corneal perforation and blindness.

15. Incubation Period

The incubation period of symptomatic gonorrhoea is commonly approximately 2–7 days after exposure.

However, symptoms may develop later, and many infections remain asymptomatic.

The incubation period varies according to the site of infection and individual host factors.

Because asymptomatic infection is common, the absence of symptoms does not exclude gonorrhoea.

Pathogenesis of Gonorrhoea

16. Colonisation of Mucosal Epithelium

Following exposure, Neisseria gonorrhoeae attaches to susceptible mucosal epithelial cells.

Type IV pili and other surface proteins facilitate adherence.

The organism can interact with and invade epithelial cells.

It may then spread locally within mucosal tissues.

The resulting infection stimulates an inflammatory response.

17. Neutrophilic Inflammation

Gonococcal infection produces a prominent neutrophilic inflammatory response.

Neutrophils migrate toward the infected mucosal surface.

The accumulation of neutrophils, bacteria and inflammatory debris produces purulent secretions.

This explains the characteristic pus-like urethral discharge associated with gonorrhoea.

Inflammation also contributes to dysuria, local irritation and mucosal tenderness.

18. Ascending Infection

Gonococcal infection may spread beyond the initial mucosal site.

In women, infection can ascend from the cervix into the endometrium and fallopian tubes.

This may produce endometritis, salpingitis and pelvic inflammatory disease.

In men, infection may occasionally extend from the urethra into the epididymis.

Ascending infection is clinically important because it may produce complications that persist after the original infection has been treated.

19. Dissemination Through the Bloodstream

Occasionally, Neisseria gonorrhoeae enters the bloodstream and causes disseminated gonococcal infection.

This may produce skin lesions, tenosynovitis, migratory polyarthralgia or septic arthritis.

Rare complications include endocarditis and meningitis.

Disseminated infection requires prompt systemic antibiotic treatment.

Clinical Features of Gonorrhoea in Men

20. Gonococcal Urethritis

Gonococcal urethritis is a classical manifestation of gonorrhoea in men.

The infection involves inflammation of the urethral mucosa.

Patients commonly develop dysuria and purulent urethral discharge.

The discharge may be thick, yellow, white or greenish.

Symptoms may develop relatively rapidly following exposure.

Gonococcal urethritis is often more symptomatic than chlamydial urethritis, although the clinical features can overlap.

21. Purulent Urethral Discharge

The most characteristic symptom of gonococcal urethritis is a pus-like discharge from the urethra.

The discharge results from the accumulation of neutrophils and inflammatory secretions.

It may be particularly noticeable in the morning or throughout the day.

The presence of prominent purulent discharge strongly suggests gonococcal urethritis.

However, laboratory testing is necessary because other infections may produce similar symptoms.

22. Dysuria

Dysuria refers to pain or burning during urination.

It occurs because the urethral epithelium becomes inflamed.

Patients may describe a sharp burning sensation while passing urine.

Dysuria may occur alongside urethral discharge or as an isolated symptom.

23. Urethral Itching and Irritation

Gonorrhoea may cause itching, tingling or discomfort within the urethra.

Some patients experience irritation at the urethral opening.

The urethral meatus may appear red or inflamed.

These symptoms reflect local mucosal inflammation.

However, urethral itching is not specific to gonorrhoea and may occur with other causes of urethritis.

24. Asymptomatic Gonorrhoea in Men

Some men with gonorrhoea have no noticeable symptoms.

Asymptomatic infection is particularly common at rectal and pharyngeal sites.

Urethral gonorrhoea is more likely to produce symptoms, but asymptomatic urethral infection can occur.

Infected individuals may transmit the organism despite feeling well.

This is an important reason for screening based on sexual exposure and risk rather than symptoms alone.

Complications of Gonorrhoea in Men

25. Epididymitis

Gonorrhoea may cause epididymitis through ascending infection from the urethra.

Patients may develop unilateral scrotal pain, swelling and tenderness.

The epididymis may become enlarged and inflamed.

Fever and urinary symptoms may also occur.

In younger sexually active men, gonorrhoea and chlamydia are important infectious causes of epididymitis.

Acute scrotal pain requires urgent assessment to exclude testicular torsion.

26. Prostatitis

The original notes identify prostatitis as a possible complication of gonorrhoea.

Gonococcal prostatitis has been described, but it is uncommon compared with other causes of bacterial prostatitis.

Patients may develop pelvic or perineal discomfort, urinary symptoms and sometimes fever.

When acute bacterial prostatitis is suspected, clinical assessment and appropriate microbiological testing are important.

27. Urethral Stricture

Historically, untreated gonococcal urethritis was an important cause of urethral strictures.

Persistent inflammation may lead to fibrosis and narrowing of the urethral lumen.

Patients may develop a weak urinary stream, difficulty initiating urination or incomplete bladder emptying.

However, urethral strictures caused by gonorrhoea are less common in settings where infection is diagnosed and treated promptly.

The association remains important in traditional medical examinations.

28. Fertility Complications in Men

Severe or recurrent infection involving the epididymis may occasionally affect male fertility.

Inflammation can damage structures involved in sperm transport.

However, infertility is a less common consequence of gonorrhoea in men than tubal infertility following pelvic inflammatory disease in women.

Early treatment reduces the risk of complications.

Clinical Features of Gonorrhoea in Women

29. Gonococcal Cervicitis

In women, gonorrhoea commonly infects the endocervix.

This may produce cervicitis, which is inflammation of the cervical mucosa.

Patients may develop mucopurulent cervical discharge, abnormal vaginal discharge or bleeding after sexual intercourse.

The cervix may appear erythematous or friable during examination.

However, many women with cervical gonorrhoea have minimal symptoms or remain asymptomatic.

30. Vaginal Discharge

Gonococcal cervicitis may produce increased vaginal discharge.

The discharge may be yellowish or mucopurulent.

However, its appearance is variable and not specific to gonorrhoea.

Other infections, including chlamydia and trichomoniasis, may produce similar symptoms.

Therefore, vaginal discharge alone cannot reliably distinguish these conditions.

31. Intermenstrual and Postcoital Bleeding

Inflammation of the cervical mucosa may make the cervix more fragile.

This can produce bleeding between menstrual periods or after sexual intercourse.

Contact bleeding may also occur during cervical examination.

These findings are compatible with cervicitis but are not specific to gonococcal infection.

32. Dysuria

Gonorrhoea may infect the female urethra.

This can produce urethritis with dysuria and urinary irritation.

Some patients may be mistaken for having a conventional urinary tract infection.

Sexual history and appropriate STI testing are therefore important when evaluating compatible symptoms.

33. Asymptomatic Gonorrhoea in Women

A substantial proportion of women with gonorrhoea are asymptomatic.

Infection may persist within the cervix without producing obvious discharge or discomfort.

Despite the absence of symptoms, the organism may ascend into the upper genital tract.

This can cause pelvic inflammatory disease and reproductive complications.

Therefore, asymptomatic gonorrhoea can still result in clinically significant harm.

Pelvic Inflammatory Disease

34. Gonorrhoea as a Cause of PID

Neisseria gonorrhoeae is an important cause of pelvic inflammatory disease.

PID occurs when infection and inflammation involve the upper female genital tract.

It may include endometritis, salpingitis, tubo-ovarian abscess and pelvic peritonitis.

Although gonorrhoea can initiate PID, the infection is frequently polymicrobial.

Other organisms, including Chlamydia trachomatis and vaginal anaerobes, may contribute.

35. Clinical Features of PID

Patients with PID may develop lower abdominal pain, pelvic tenderness, fever and abnormal vaginal discharge.

Dyspareunia, intermenstrual bleeding and postcoital bleeding may also occur.

Pelvic examination may reveal cervical motion tenderness, uterine tenderness or adnexal tenderness.

However, symptoms may be mild or non-specific.

PID may occasionally occur without prominent fever or obvious genital discharge.

36. Salpingitis

Salpingitis refers to inflammation of the fallopian tubes.

It can develop when gonococcal infection ascends from the cervix.

Inflammation may damage the tubal epithelium and impair normal ciliary function.

Severe or recurrent inflammation can cause scarring and adhesions.

This may interfere with the normal transport of the ovum.

37. Tubal Infertility

Gonococcal PID can cause infertility through damage to the fallopian tubes.

Inflammation may produce fibrosis, adhesions and tubal obstruction.

When the tubes become damaged, fertilisation may be impaired.

The risk of infertility increases with repeated episodes of PID.

Antibiotics can treat the infection but may not reverse established structural damage.

38. Ectopic Pregnancy

Fallopian tube damage following PID increases the risk of ectopic pregnancy.

Scarring and impaired ciliary function may prevent normal transport of the fertilised ovum.

This increases the likelihood of implantation within the fallopian tube.

A ruptured ectopic pregnancy can produce severe intra-abdominal haemorrhage and is a medical emergency.

39. Chronic Pelvic Pain

Gonorrhoea-associated PID may result in chronic pelvic pain.

Persistent pain can occur because of pelvic adhesions and structural damage.

Symptoms may continue after the infection has been eradicated.

This highlights the importance of early diagnosis and treatment.

40. Fitz-Hugh–Curtis Syndrome

Fitz-Hugh–Curtis syndrome is perihepatitis associated with pelvic inflammatory disease.

It involves inflammation of the liver capsule.

Patients may experience right upper quadrant abdominal pain.

Laparoscopy may demonstrate characteristic violin-string adhesions between the liver capsule and surrounding structures.

Both gonorrhoea and chlamydia may be associated with this syndrome.

Extragenital Gonorrhoea

41. Rectal Gonorrhoea

Rectal gonorrhoea may occur following exposure of the rectal mucosa.

Many infections are asymptomatic.

When symptoms occur, they may include rectal pain, discharge, bleeding, tenesmus or discomfort during defecation.

Rectal infection can coexist with genital or pharyngeal gonorrhoea.

Diagnosis is usually established using an appropriately validated rectal NAAT.

42. Pharyngeal Gonorrhoea

Pharyngeal gonorrhoea occurs following exposure of the oropharyngeal mucosa.

Most patients are asymptomatic.

Some develop sore throat or pharyngeal irritation.

Pharyngeal infection is important because it may contribute to ongoing transmission and is more difficult to eradicate reliably than urogenital infection.

A test of cure is commonly recommended after treatment of pharyngeal gonorrhoea.

43. Gonococcal Conjunctivitis in Adults

Gonococcal conjunctivitis can occur when infected secretions contact the eye.

It may produce marked conjunctival redness, eyelid swelling and copious purulent discharge.

The infection can progress rapidly and cause corneal ulceration.

Without prompt treatment, corneal perforation and visual loss may occur.

Suspected gonococcal conjunctivitis requires urgent medical and ophthalmological assessment.

Neonatal Gonorrhoea

44. Gonococcal Ophthalmia Neonatorum

Gonococcal ophthalmia neonatorum is a severe neonatal conjunctival infection caused by Neisseria gonorrhoeae.

It usually develops approximately 2–5 days after birth.

The infant may develop pronounced eyelid swelling, conjunctival inflammation and copious purulent discharge.

The infection can rapidly involve the cornea.

Without treatment, corneal ulceration, perforation and blindness may occur.

This condition requires urgent systemic antibiotic treatment.

45. Prevention of Neonatal Gonorrhoea

Prevention involves identifying and treating maternal gonococcal infection during pregnancy.

Neonatal ocular prophylaxis is used in some healthcare systems according to national recommendations.

However, prophylaxis does not replace maternal screening and treatment.

Infants with suspected gonococcal conjunctivitis require prompt evaluation and systemic therapy.

Disseminated Gonococcal Infection

46. Introduction to Disseminated Gonococcal Infection

Disseminated gonococcal infection (DGI) occurs when Neisseria gonorrhoeae spreads through the bloodstream.

It is an uncommon but important complication of gonorrhoea.

DGI may occur even when the original genital infection produces few or no symptoms.

The infection can involve joints, tendon sheaths and skin.

Two major presentations are the arthritis-dermatitis syndrome and purulent gonococcal arthritis.

47. Arthritis-Dermatitis Syndrome

The classical arthritis-dermatitis syndrome is characterised by a combination of migratory polyarthralgia, tenosynovitis and skin lesions.

Patients may experience pain affecting several joints.

Tenosynovitis commonly involves tendons of the hands, wrists, ankles or feet.

Skin lesions may be sparse and can appear as pustules or vesiculopustular lesions, sometimes with haemorrhagic features.

The complete triad is not present in every patient.

48. Gonococcal Septic Arthritis

Gonorrhoea may cause septic arthritis through haematogenous dissemination.

Patients may develop acute pain, swelling and reduced movement in an affected joint.

The knee, wrist and ankle are among the commonly involved joints.

Joint aspiration and appropriate microbiological testing are important when septic arthritis is suspected.

This condition requires urgent antibiotic treatment and may require joint drainage.

49. Rare Disseminated Complications

Rare manifestations of disseminated gonococcal infection include endocarditis and meningitis.

These complications can be severe and potentially life-threatening.

They require hospital-based investigation and prolonged antimicrobial treatment.

Diagnosis of Gonorrhoea

50. Clinical Diagnosis

Gonorrhoea should be suspected in sexually active patients presenting with purulent urethral discharge, dysuria, cervicitis or compatible rectal and pharyngeal symptoms.

A history of recent sexual exposure may support the diagnosis.

However, clinical features alone cannot reliably distinguish gonorrhoea from other sexually transmitted infections.

Many patients are asymptomatic, particularly those with cervical, rectal or pharyngeal infection.

Laboratory confirmation is therefore important.

51. Gram Staining

Gram staining is a traditional diagnostic method for gonorrhoea.

A urethral swab is collected and examined microscopically.

The characteristic finding is intracellular Gram-negative diplococci within polymorphonuclear neutrophils.

In symptomatic men with urethral discharge, this finding has high diagnostic specificity.

However, Gram staining is less sensitive and specific for cervical, rectal and pharyngeal specimens.

A negative Gram stain does not exclude gonorrhoea.

52. Nucleic Acid Amplification Testing

Nucleic acid amplification testing (NAAT) is the preferred routine diagnostic method for gonorrhoea in many clinical settings.

NAAT detects genetic material from Neisseria gonorrhoeae.

It provides high sensitivity and specificity when used with validated specimens.

Depending on the anatomical site, samples may include first-catch urine, vaginal swabs, cervical swabs, rectal swabs and pharyngeal swabs.

NAAT can also detect infection in asymptomatic individuals.

However, NAAT does not routinely provide antimicrobial susceptibility information.

53. Specimen Collection

In men, first-catch urine is commonly used for detecting urethral gonorrhoea.

A urethral swab may be obtained when discharge is present, particularly if microscopy or culture is required.

In women, vaginal swabs are generally suitable for NAAT.

Rectal and pharyngeal swabs should be collected when indicated by exposure history or screening recommendations.

Sampling the correct anatomical sites is important because genital testing alone may miss extragenital infection.

54. Gonococcal Culture

Culture remains important in gonorrhoea diagnosis because it allows the organism to be isolated and tested for antibiotic susceptibility.

Specimens may be inoculated onto selective media, including modified Thayer–Martin medium.

The organism requires suitable transport and laboratory conditions because it is relatively fragile outside the host.

Culture is particularly important when antimicrobial resistance or treatment failure is suspected.

Although NAAT is more convenient for routine diagnosis, culture is essential for assessing antimicrobial susceptibility.

55. Antibiotic Susceptibility Testing

Antimicrobial susceptibility testing determines whether an isolated gonococcal strain is susceptible or resistant to particular antibiotics.

This is increasingly important because Neisseria gonorrhoeae has developed resistance to multiple antimicrobial classes.

Testing may assess susceptibility to ceftriaxone, ciprofloxacin and other agents.

Results can guide treatment when standard therapy is unsuitable or treatment failure is suspected.

Surveillance of antimicrobial resistance is also essential for maintaining effective national treatment guidelines.

Treatment of Gonorrhoea

56. Principles of Treatment

Treatment aims to eradicate Neisseria gonorrhoeae, relieve symptoms, prevent complications and reduce transmission.

Antibiotic selection must account for local antimicrobial resistance patterns.

This is especially important because gonorrhoea has developed resistance to several drugs that were previously effective.

The preferred treatment for uncomplicated gonorrhoea is generally ceftriaxone.

Patients should also be assessed for associated sexually transmitted infections, particularly chlamydia.

57. Ceftriaxone

Ceftriaxone is a third-generation cephalosporin antibiotic.

It inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins.

This interferes with peptidoglycan cross-linking and compromises bacterial cell wall integrity.

Ceftriaxone has bactericidal activity against susceptible Neisseria gonorrhoeae.

It is the principal recommended treatment for uncomplicated gonorrhoea in current UK and US guidelines.

However, reduced susceptibility and ceftriaxone-resistant gonococcal strains have been reported, making continued resistance surveillance essential.

58. Recommended Treatment in the United Kingdom

The 2025 British Association for Sexual Health and HIV (BASHH) guideline recommends:

Ceftriaxone 1 g intramuscularly as a single dose for uncomplicated anogenital and pharyngeal gonorrhoea in adults.

Alternative regimens may be considered in selected circumstances, particularly when ceftriaxone cannot be administered.

The choice of an alternative should account for antimicrobial susceptibility, allergy history and specialist guidance. BASHH +1

59. Recommended Treatment in the United States

The CDC guideline recommends:

Ceftriaxone 500 mg intramuscularly as a single dose for uncomplicated gonorrhoea in patients weighing less than 150 kg.

For patients weighing 150 kg or more, the recommended dose is 1 g intramuscularly.

If chlamydial infection has not been excluded, doxycycline 100 mg orally twice daily for seven days is also recommended in appropriate non-pregnant patients.

These differences demonstrate why treatment should follow the relevant national guideline. STI Treatment Guidelines

60. Penicillin

Penicillin was historically used to treat gonorrhoea.

It inhibits bacterial cell wall synthesis by interfering with peptidoglycan cross-linking.

However, Neisseria gonorrhoeae has developed substantial resistance to penicillin through several mechanisms.

These include beta-lactamase production and alterations in penicillin-binding proteins.

Consequently, penicillin is not recommended for routine empirical treatment of gonorrhoea.

This is an important correction to older medical textbooks.

61. Ciprofloxacin

Ciprofloxacin is a fluoroquinolone antibiotic.

It inhibits bacterial DNA gyrase and topoisomerase IV, disrupting bacterial DNA replication.

Ciprofloxacin was previously widely used to treat gonorrhoea.

However, widespread fluoroquinolone resistance has limited its usefulness.

It should not be used routinely as empirical treatment.

In selected cases, ciprofloxacin may be considered when susceptibility is confirmed and its use is clinically appropriate. Sage Journals

62. Tetracyclines

Tetracyclines inhibit bacterial protein synthesis by binding to the 30S ribosomal subunit.

Historically, tetracyclines were used for gonococcal infection.

However, resistance has made them unreliable for treating gonorrhoea.

Doxycycline remains important for treating associated Chlamydia trachomatis infection.

Doxycycline alone is not an appropriate treatment for gonorrhoea.

63. Antimicrobial Resistance

Antimicrobial resistance is one of the most important modern concerns in gonorrhoea management.

Neisseria gonorrhoeae has developed resistance to several antibiotic classes, including penicillins, tetracyclines, fluoroquinolones and macrolides.

Reduced susceptibility and resistance to extended-spectrum cephalosporins have also emerged.

Resistance may arise through chromosomal mutations, altered drug targets, efflux mechanisms and other bacterial adaptations.

The development of resistant strains makes microbiological surveillance and appropriate antibiotic selection essential.

64. Treatment of Gonorrhoea During Pregnancy

Gonorrhoea during pregnancy requires treatment because untreated infection may contribute to maternal complications and neonatal transmission.

Ceftriaxone is commonly recommended.

Treatment should follow appropriate national guidance.

If chlamydial coinfection is present, an antibiotic suitable for pregnancy must also be selected.

Pregnant patients may require additional follow-up to confirm successful treatment.

65. Treatment of Gonococcal PID

Gonococcal PID requires broader antimicrobial coverage than uncomplicated gonorrhoea.

This is because PID may involve Neisseria gonorrhoeae, Chlamydia trachomatis and anaerobic organisms.

A commonly recommended outpatient approach includes ceftriaxone, doxycycline and metronidazole, with exact doses and duration determined by the applicable PID guideline.

Ceftriaxone provides gonococcal coverage.

Doxycycline treats chlamydia and other susceptible organisms.

Metronidazole provides anaerobic coverage.

Severe PID may require hospitalisation and intravenous antibiotics.

66. Treatment of Disseminated Gonococcal Infection

Disseminated gonococcal infection requires systemic antibiotic treatment.

Ceftriaxone is commonly used intravenously or intramuscularly.

For gonococcal arthritis and arthritis-dermatitis syndrome, the UK guideline recommends ceftriaxone 1 g every 24 hours initially, with subsequent treatment determined by clinical response and susceptibility.

Complications such as endocarditis or meningitis require longer treatment courses and specialist management. Sage Journals

Follow-Up and Prevention

67. Test of Cure

A test of cure is performed to determine whether gonorrhoea has been successfully eradicated.

The need for testing depends on the anatomical site, treatment regimen, antimicrobial susceptibility and applicable guidelines.

Under the 2025 UK guideline, a test of cure is recommended in several situations, including pharyngeal infection, persistent symptoms, unknown antimicrobial susceptibility, pregnancy and use of treatment other than ceftriaxone.

Routine test of cure may not be necessary for susceptible anogenital infection treated with the recommended ceftriaxone regimen.

Testing should be performed at an appropriate interval to avoid misleading results from residual bacterial nucleic acid. BASHH

68. Reinfection

Gonorrhoea can occur repeatedly.

Previous infection does not provide reliable long-term protective immunity.

This is partly related to antigenic variation in gonococcal surface structures.

Reinfection commonly occurs when sexual partners remain untreated or when a patient has a new exposure.

Retesting approximately three months after treatment is commonly recommended because reinfection is frequent.

69. Treatment of Sexual Partners

Sexual partner management is essential for controlling gonorrhoea.

Recent sexual partners should be assessed, tested and treated according to relevant guidelines.

Patients should avoid sexual contact until treatment has been completed and the recommended abstinence period has passed.

The UK guideline advises abstaining until seven days after both the patient and their partner or partners have completed treatment.

Appropriate partner management reduces reinfection and ongoing transmission. BASHH

70. Screening for Other Sexually Transmitted Infections

Patients diagnosed with gonorrhoea should be assessed for other sexually transmitted infections.

Testing commonly includes chlamydia, syphilis and HIV.

This is important because coinfection may occur.

Identifying additional infections allows appropriate treatment and reduces the risk of complications.

71. Safer Sexual Practices

Consistent and correct condom use reduces the risk of gonorrhoea transmission.

However, no barrier method eliminates all STI transmission risk.

Regular STI screening may be appropriate for individuals with ongoing exposure risk.

Early diagnosis, effective treatment and partner notification are important preventive measures.

Gonorrhoea and Chlamydia – Important Distinction

72. Gonococcal Urethritis

Gonococcal urethritis is caused by Neisseria gonorrhoeae.

It classically produces prominent purulent urethral discharge and dysuria.

The organism is a Gram-negative diplococcus.

Microscopy may demonstrate intracellular Gram-negative diplococci within neutrophils.

Treatment generally involves ceftriaxone.

73. Chlamydial Urethritis

Chlamydial urethritis is caused by Chlamydia trachomatis.

It often produces milder symptoms and scanty mucoid or mucopurulent discharge.

Many infections are asymptomatic.

The organism is an obligate intracellular bacterium.

Diagnosis is usually established using NAAT.

Treatment generally involves doxycycline in non-pregnant adults.

74. Coinfection

Gonorrhoea and chlamydia can occur simultaneously.

Both organisms can cause urethritis, cervicitis and pelvic inflammatory disease.

Because clinical features overlap, patients with suspected gonorrhoea are commonly tested for chlamydia.

When chlamydial infection has not been excluded, additional treatment may be required according to the relevant guideline.

Important Corrections to the Original Notes

75. Large Asymptomatic Population

The original statement that many patients with gonorrhoea are asymptomatic is correct.

However, the frequency of asymptomatic infection depends on the anatomical site.

Urethral gonorrhoea in men is frequently symptomatic.

Cervical, rectal and pharyngeal infections are more commonly asymptomatic.

76. Diagnosis by Urethral Swab

The original notes correctly identify Gram-negative diplococci as a characteristic microscopic finding.

However, NAAT is now the preferred routine diagnostic method in many settings.

Gram staining remains particularly useful for symptomatic male urethritis.

Culture is important when antimicrobial susceptibility testing is required.

77. Antibiotic Sensitivity in the United Kingdom

The original notes state that gonorrhoea in the UK is predominantly sensitive to penicillin, ciprofloxacin, cephalosporins and tetracycline.

This is outdated and should not be used to guide current treatment.

Resistance to penicillins, tetracyclines and fluoroquinolones is widespread.

The current UK first-line recommendation is ceftriaxone 1 g intramuscularly as a single dose.

Ciprofloxacin may be considered in selected circumstances when susceptibility is confirmed, but it is not recommended as routine first-line treatment. BASHH +1

78. Complications of Untreated Gonorrhoea

The original notes correctly identify PID, epididymitis, prostatitis and urethral strictures as possible complications.

However, prostatitis and urethral strictures are relatively uncommon complications in modern clinical practice.

Other important complications include tubal infertility, ectopic pregnancy, disseminated gonococcal infection and neonatal ophthalmia.

Important Clinical Associations – Note Form

79. Neisseria gonorrhoeae

Neisseria gonorrhoeae is a Gram-negative diplococcus.

It is oxidase-positive and classically utilises glucose but not maltose.

It infects mucosal surfaces of the urethra, cervix, rectum, pharynx and conjunctiva.

80. Gram Staining

The characteristic finding is intracellular Gram-negative diplococci within neutrophils.

This is particularly useful in symptomatic male urethritis.

81. Gonococcal Urethritis

Gonococcal urethritis classically causes purulent urethral discharge and dysuria.

Symptoms often develop within several days of exposure.

82. Gonococcal Cervicitis

Gonococcal cervicitis may produce mucopurulent cervical discharge, cervical friability and abnormal bleeding.

Many patients remain asymptomatic.

83. Pelvic Inflammatory Disease

Ascending gonococcal infection can cause PID.

Complications include salpingitis, infertility, ectopic pregnancy and chronic pelvic pain.

84. Epididymitis

Gonorrhoea may cause epididymitis through ascending infection.

Patients may develop unilateral scrotal pain and swelling.

85. Disseminated Gonococcal Infection

Disseminated infection classically produces migratory polyarthralgia, tenosynovitis and pustular skin lesions.

It may also cause septic arthritis.

86. Gonococcal Ophthalmia Neonatorum

Neonatal gonococcal conjunctivitis typically develops 2–5 days after birth.

It produces severe purulent conjunctivitis and may rapidly cause corneal damage.

87. NAAT

NAAT is the preferred routine diagnostic test for gonorrhoea in many settings.

It can detect infection in urine and appropriate genital or extragenital swabs.

88. Culture and Sensitivity

Gonococcal culture allows antimicrobial susceptibility testing.

It is particularly important when antibiotic resistance or treatment failure is suspected.

89. Ceftriaxone

Ceftriaxone is a third-generation cephalosporin.

It inhibits bacterial cell wall synthesis.

It is the principal recommended antibiotic for uncomplicated gonorrhoea.

90. Antimicrobial Resistance

Gonorrhoea has developed resistance to multiple antimicrobial classes.

Penicillin, tetracycline and ciprofloxacin should not be assumed effective.

Antibiotic treatment should follow current national guidelines and susceptibility results where appropriate.

Key Clinical Pattern

The defining feature of gonorrhoea is mucosal infection caused by the Gram-negative diplococcus Neisseria gonorrhoeae, classically producing purulent urethral discharge and dysuria, with potential complications involving the reproductive tract and disseminated infection.

Neisseria gonorrhoeae → Gram-negative, oxidase-positive diplococcus.

Microscopy → Intracellular Gram-negative diplococci within neutrophils.

Transmission → Vaginal, anal and oral sexual contact.

Men → Purulent urethral discharge, dysuria and urethral irritation.

Women → Cervicitis, often asymptomatic.

Ascending infection → Pelvic inflammatory disease and salpingitis.

PID complications → Tubal infertility, ectopic pregnancy and chronic pelvic pain.

Male complications → Epididymitis; less commonly prostatitis or urethral stricture.

Disseminated gonorrhoea → Tenosynovitis, migratory polyarthralgia and pustular skin lesions.

Neonatal gonorrhoea → Severe purulent conjunctivitis developing approximately 2–5 days after birth.

NAAT → Preferred routine diagnostic test.

Culture → Important for antimicrobial susceptibility testing.

Ceftriaxone → First-line antibiotic for uncomplicated gonorrhoea.

Penicillin, tetracycline and ciprofloxacin → Historical treatments limited by antimicrobial resistance.

Partner management → Essential for preventing reinfection and transmission.

For examinations, remember the classical association: Neisseria gonorrhoeae is a Gram-negative diplococcus that causes purulent urethritis in men, cervicitis and PID in women, and neonatal ophthalmia. Intracellular Gram-negative diplococci are characteristic on urethral microscopy, while ceftriaxone is the principal modern treatment.

Medicine – Chlamydial Infection: Aetiology, Transmission, Pathogenesis, Clinical Features, Diagnosis and Treatment

1. Introduction to Chlamydial Infection

Chlamydial infection is a common sexually transmitted infection (STI) caused by Chlamydia trachomatis, an obligate intracellular bacterium that primarily infects epithelial cells of the genitourinary tract.

It is one of the most important causes of non-gonococcal urethritis (NGU) in men and cervicitis and pelvic inflammatory disease (PID) in women.

An important feature of chlamydial infection is that many infected individuals remain asymptomatic. Despite the absence of symptoms, the organism can persist, cause inflammation and produce complications.

In women, untreated infection may ascend from the cervix into the upper genital tract, causing salpingitis, pelvic inflammatory disease, tubal damage, ectopic pregnancy and infertility.

Chlamydia may also be transmitted from an infected mother to her infant during childbirth, causing neonatal conjunctivitis or pneumonia.

The infection is treatable with antibiotics, particularly doxycycline, although treatment selection depends on pregnancy status, age and the clinical syndrome.

2. Aetiological Agent – Chlamydia trachomatis

The causative organism is Chlamydia trachomatis, a small, Gram-negative-like bacterium belonging to the family Chlamydiaceae.

Unlike most bacteria, Chlamydia trachomatis cannot complete its reproductive cycle independently outside a host cell.

It is therefore described as an obligate intracellular bacterium.

The organism preferentially infects columnar epithelial cells lining the cervix, urethra, rectum and conjunctiva.

Different serovars of Chlamydia trachomatis are associated with different clinical syndromes, including sexually transmitted infections, trachoma and lymphogranuloma venereum.

3. Classification of Chlamydia trachomatis Serovars

Chlamydia trachomatis is classified into serovars according to antigenic differences.

Serovars A, B, Ba and C are associated with trachoma, a chronic ocular infection that can cause conjunctival scarring and blindness.

Serovars D–K are responsible for most sexually transmitted urogenital chlamydial infections.

These serovars may also cause neonatal conjunctivitis and pneumonia following exposure during childbirth.

Serovars L1, L2 and L3 cause lymphogranuloma venereum (LGV), a more invasive sexually transmitted infection that can produce lymphadenopathy and proctocolitis.

This classification is important because the clinical manifestations and treatment durations may differ.

Microbiology and Pathogenesis

4. Obligate Intracellular Nature

Chlamydia trachomatis requires living host cells for replication.

It cannot reproduce using the same extracellular mechanisms as many conventional bacteria.

The organism has a distinctive developmental cycle involving two principal forms: the elementary body and the reticulate body.

These forms perform different functions during infection.

The elementary body is adapted for transmission and entry into host cells, whereas the reticulate body is adapted for intracellular replication.

5. Elementary Body

The elementary body (EB) is the small, infectious extracellular form of Chlamydia trachomatis.

It is metabolically relatively inactive and structurally adapted to survive outside host cells for a limited period.

The elementary body attaches to susceptible epithelial cells and enters through an endocytic process.

Once inside the host cell, it begins transforming into the reticulate body.

The elementary body is therefore responsible for initiating infection.

6. Reticulate Body

The reticulate body (RB) is the larger, metabolically active, non-infectious intracellular form.

After transformation from the elementary body, the reticulate body replicates within a membrane-bound intracellular inclusion.

Replication occurs by binary fission.

Following multiplication, reticulate bodies differentiate back into elementary bodies.

The newly formed elementary bodies are subsequently released and infect neighbouring epithelial cells.

This cycle contributes to the spread of infection and the development of local inflammation.

7. Pathogenesis of Tissue Injury

Chlamydial infection causes tissue injury through direct effects on infected epithelial cells and the host inflammatory response.

The organism replicates within epithelial cells and stimulates the release of inflammatory mediators.

These mediators recruit immune cells to the infected tissues.

Persistent or repeated inflammation can produce epithelial damage, fibrosis and scarring.

In the female reproductive tract, scarring of the fallopian tubes is particularly important because it may impair fertility.

Therefore, the major complications of chlamydial infection often result from inflammation and subsequent tissue damage, rather than simply the presence of the organism.

Transmission of Chlamydial Infection

8. Sexual Transmission

Chlamydia trachomatis is transmitted predominantly through sexual contact.

Transmission may occur during vaginal, anal or oral sexual activity.

The organism infects susceptible mucosal surfaces, particularly those lined by columnar epithelium.

Infection may involve the cervix, urethra, rectum or pharynx.

Transmission can occur even when the infected individual has no symptoms.

This is clinically important because asymptomatic infection contributes substantially to the continued spread of chlamydia.

9. Vertical Transmission

Chlamydia may be transmitted from an infected mother to her infant during childbirth.

The infant becomes exposed to infected genital secretions during passage through the birth canal.

This can lead to infection of the neonatal conjunctiva or respiratory tract.

The two classical neonatal manifestations are inclusion conjunctivitis and afebrile pneumonia.

Appropriate maternal screening and treatment during pregnancy reduce the risk of neonatal infection.

10. Incubation Period

The incubation period of symptomatic urogenital chlamydial infection is commonly approximately 1–3 weeks.

However, many infections remain asymptomatic.

Symptoms may develop gradually and may be mild.

Because the timing of symptom onset is variable, it is often difficult to determine exactly when infection was acquired.

Untreated infection may persist for prolonged periods.

Chlamydial Infection in Men

11. Non-Gonococcal Urethritis

Chlamydia is a major cause of non-gonococcal urethritis (NGU), historically also called non-specific urethritis (NSU).

Urethritis refers to inflammation of the urethral mucosa.

The original notes state that Chlamydia trachomatis is responsible for more than 50% of cases of non-specific urethritis.

This is a traditional teaching association, but the proportion varies considerably between populations.

Modern estimates generally attribute approximately 15–40% of NGU cases to Chlamydia trachomatis, rather than consistently more than 50%.

Other causes include Mycoplasma genitalium, Trichomonas vaginalis and certain viral infections.

12. Clinical Features of Chlamydial Urethritis

Chlamydial urethritis may produce dysuria, urethral irritation and urethral discharge.

The discharge is often scanty, clear or mucoid, although it may occasionally be mucopurulent.

Patients may complain of burning during urination or discomfort at the urethral opening.

Symptoms are often milder than those associated with gonococcal urethritis.

However, the clinical features overlap, and the two infections cannot be reliably distinguished by symptoms alone.

13. Asymptomatic Urethral Infection

Many men with urethral chlamydial infection have no noticeable symptoms.

Despite the absence of symptoms, infection may persist within the urethral epithelium.

Asymptomatic individuals can transmit the organism to sexual partners.

This is one reason chlamydia remains common despite the availability of effective antibiotic treatment.

14. Epididymitis

Chlamydia may ascend from the urethra into the epididymis, causing epididymitis.

The epididymis is a coiled tubular structure located behind the testis that is involved in sperm maturation and transport.

Patients may develop unilateral scrotal pain, swelling and tenderness.

Dysuria or urethral discharge may also be present.

In sexually active younger men, Chlamydia trachomatis and Neisseria gonorrhoeae are important causes of epididymitis.

Acute severe testicular pain requires urgent assessment to exclude testicular torsion.

15. Reactive Arthritis

Chlamydial infection may trigger reactive arthritis.

Reactive arthritis is an inflammatory joint disorder that develops following certain gastrointestinal or genitourinary infections.

The arthritis is sterile, meaning that viable organisms are generally not present within the affected joint.

Patients may develop asymmetric oligoarthritis, commonly involving the knees, ankles or feet.

Enthesitis, dactylitis and inflammatory back pain may also occur.

Some patients develop conjunctivitis or uveitis.

The classical association is urethritis, arthritis and conjunctivitis, although the complete triad is not always present.

Chlamydial Infection in Women

16. Cervicitis

Chlamydia commonly infects the columnar epithelial cells of the endocervix.

This may produce cervicitis, which is inflammation of the cervix.

Patients may develop abnormal vaginal discharge, intermenstrual bleeding or postcoital bleeding.

On examination, the cervix may appear inflamed or friable.

Mucopurulent discharge may be visible at the cervical opening.

However, many women with cervical chlamydial infection remain asymptomatic.

17. Clinical Features of Chlamydial Cervicitis

Symptomatic cervicitis may produce increased vaginal discharge, pelvic discomfort or bleeding after sexual intercourse.

The discharge may be mucopurulent because of inflammatory cells and cervical secretions.

Dysuria may occur if the urethra is also infected.

Cervical friability can cause contact bleeding during examination.

These findings are not specific to chlamydia because gonorrhoea and other infections may produce similar manifestations.

18. Ascending Genital Tract Infection

Untreated cervical infection may ascend into the upper female reproductive tract.

The organism can spread from the cervix into the endometrium and fallopian tubes.

This may produce endometritis and salpingitis.

The resulting inflammation can damage the reproductive tract.

In some patients, this progresses to pelvic inflammatory disease.

Ascending infection is clinically important because it may cause permanent reproductive complications even when the initial cervical infection was mild or asymptomatic.

Pelvic Inflammatory Disease

19. Introduction to Pelvic Inflammatory Disease

Pelvic inflammatory disease (PID) refers to infection and inflammation involving the upper female genital tract.

It may include endometritis, salpingitis, tubo-ovarian abscess and pelvic peritonitis.

Chlamydia trachomatis is an important cause of PID.

Neisseria gonorrhoeae and other organisms, including vaginal anaerobes, may also contribute.

PID is frequently polymicrobial.

The major concern is that inflammation may damage the fallopian tubes and surrounding pelvic structures.

20. Clinical Features of PID

Patients with PID commonly present with lower abdominal or pelvic pain.

Other symptoms may include abnormal vaginal discharge, fever, dyspareunia, intermenstrual bleeding or postcoital bleeding.

On pelvic examination, cervical motion tenderness, uterine tenderness or adnexal tenderness may be present.

However, PID may produce mild or non-specific symptoms.

Some patients develop significant upper genital tract inflammation without recognising that they have an infection.

21. Salpingitis

Salpingitis is inflammation of the fallopian tubes.

It commonly develops when organisms ascend from the cervix into the upper genital tract.

Chlamydial infection can produce inflammation of the tubal epithelium.

Persistent inflammation may damage ciliated epithelial cells and cause fibrosis.

This can interfere with the transport of the ovum through the fallopian tube.

The resulting tubal damage is a major mechanism of chlamydia-associated infertility and ectopic pregnancy.

22. Tubal Infertility

Untreated chlamydial infection can cause infertility through damage to the fallopian tubes.

Inflammation may produce scarring, adhesions and partial or complete tubal obstruction.

Normally, the fallopian tubes transport the ovum and provide the usual site of fertilisation.

When the tubes become obstructed or damaged, sperm and ova may be unable to meet.

This reduces the likelihood of natural conception.

Chlamydia is therefore an important preventable cause of tubal-factor infertility.

The risk increases with repeated or severe episodes of upper genital tract infection.

23. Ectopic Pregnancy

Chlamydial salpingitis increases the risk of ectopic pregnancy.

An ectopic pregnancy occurs when implantation takes place outside the uterine cavity.

The most common location is the fallopian tube.

Tubal inflammation and scarring may impair transport of the fertilised ovum.

This increases the likelihood of implantation within the tube.

A ruptured ectopic pregnancy can cause life-threatening intra-abdominal haemorrhage.

Therefore, ectopic pregnancy must be considered in a patient of reproductive potential presenting with pelvic pain and a positive pregnancy test.

24. Chronic Pelvic Pain

PID may result in chronic pelvic pain.

Persistent discomfort can arise from inflammation, pelvic adhesions or damage to reproductive structures.

The pain may continue even after the original infection has been successfully treated.

This occurs because antibiotics eliminate susceptible organisms but cannot necessarily reverse established tissue scarring.

Early recognition and treatment of chlamydial infection are therefore important for preventing long-term complications.

25. Fitz-Hugh–Curtis Syndrome

Fitz-Hugh–Curtis syndrome is perihepatitis associated with pelvic inflammatory disease.

It involves inflammation of the liver capsule rather than primary infection of the liver parenchyma.

Patients may develop right upper quadrant abdominal pain, sometimes resembling gallbladder disease.

Laparoscopy may reveal characteristic thin adhesions between the liver capsule and abdominal wall.

These are classically described as violin-string adhesions.

Both Chlamydia trachomatis and Neisseria gonorrhoeae may be associated with this syndrome.

Neonatal Chlamydial Infection

26. Introduction to Neonatal Chlamydia

Neonatal chlamydial infection usually results from exposure to maternal genital infection during childbirth.

The organism may infect the conjunctiva or respiratory tract.

The two important manifestations are neonatal inclusion conjunctivitis and chlamydial pneumonia.

Both conditions are associated mainly with Chlamydia trachomatis serovars D–K.

27. Neonatal Inclusion Conjunctivitis

Neonatal inclusion conjunctivitis is an ocular infection caused by Chlamydia trachomatis.

It typically develops approximately 5–12 days after birth.

The infant may develop conjunctival redness, eyelid swelling and mucopurulent ocular discharge.

The infection can affect one or both eyes.

Because the organism may also be present in the respiratory tract, systemic antibiotic treatment is necessary.

Topical eye treatment alone is insufficient.

28. Chlamydial Pneumonia in Neonates

Chlamydial pneumonia is another recognised manifestation of perinatally acquired infection.

It typically develops between 1 and 3 months of age.

The illness is often gradual in onset.

Infants may develop tachypnoea and a characteristic repetitive, staccato cough.

Fever is usually absent.

This presentation is commonly described as afebrile pneumonia of infancy.

29. Clinical Features of Neonatal Chlamydial Pneumonia

Infants with chlamydial pneumonia may present with persistent cough, rapid breathing and feeding difficulties.

The cough may have a characteristic staccato pattern, consisting of short, repetitive bursts.

Chest imaging may demonstrate bilateral diffuse interstitial infiltrates or hyperinflation.

Peripheral blood eosinophilia may also occur.

The infection generally develops gradually rather than producing the abrupt severe illness associated with some bacterial pneumonias.

30. Treatment of Neonatal Chlamydial Infection

Neonatal chlamydial conjunctivitis and pneumonia require systemic antibiotic treatment.

Oral erythromycin is a recognised treatment option.

Azithromycin may also be used in selected circumstances.

Treatment choice depends on age, clinical presentation and applicable paediatric guidance.

Macrolide treatment in young infants is associated with a risk of infantile hypertrophic pyloric stenosis, particularly during early infancy.

Therefore, treated infants should be monitored appropriately.

Other Clinical Manifestations of Chlamydia trachomatis

31. Trachoma

Trachoma is a chronic ocular infection caused by Chlamydia trachomatis serovars A, B, Ba and C.

It is transmitted through contact with infected ocular or nasal secretions, including through contaminated hands and certain flies.

Repeated infection produces chronic conjunctival inflammation.

Over time, conjunctival scarring may cause the eyelashes to turn inward, a condition called trichiasis.

The eyelashes may damage the cornea, eventually causing corneal opacity and blindness.

Trachoma is an important preventable cause of infectious blindness worldwide.

32. Lymphogranuloma Venereum

Lymphogranuloma venereum (LGV) is caused by Chlamydia trachomatis serovars L1, L2 and L3.

Unlike the more superficial infections caused by serovars D–K, LGV is relatively invasive and may involve lymphatic tissues.

The initial lesion may be a small, transient genital ulcer that goes unnoticed.

Subsequently, patients may develop painful regional lymphadenopathy.

Inguinal lymph nodes may become enlarged and form buboes.

LGV may also produce severe proctocolitis, particularly following rectal exposure.

33. Treatment of Lymphogranuloma Venereum

LGV requires a longer antibiotic course than uncomplicated urogenital chlamydial infection.

The standard adult regimen is doxycycline 100 mg orally twice daily for 21 days.

This prolonged course is used because LGV is more invasive and may involve deeper tissues and lymphatic structures.

Patients with severe complications may require additional assessment and management.

Diagnosis of Chlamydial Infection

34. Clinical Suspicion

Chlamydial infection should be considered in sexually active patients presenting with urethritis, cervicitis, pelvic pain or compatible complications.

However, clinical findings alone are insufficient for diagnosis.

Many infected individuals are asymptomatic.

Furthermore, chlamydia and gonorrhoea can produce similar symptoms and may occur together.

Laboratory testing is therefore essential for accurate diagnosis.

35. Nucleic Acid Amplification Testing

Nucleic acid amplification testing (NAAT) is the preferred diagnostic method for Chlamydia trachomatis infection.

NAAT detects chlamydial genetic material.

It offers high sensitivity and specificity.

Depending on the anatomical site and assay, suitable specimens include first-catch urine, vaginal swabs, cervical swabs and rectal swabs.

Pharyngeal specimens may also be tested when appropriate.

NAAT has largely replaced older diagnostic methods for routine urogenital chlamydial infection.

36. Specimen Collection

In men, first-catch urine is commonly used for detecting urethral chlamydial infection.

In women, vaginal swabs are generally preferred because they provide excellent diagnostic sensitivity.

Self-collected vaginal swabs can be suitable when supported by the test and clinical service.

Rectal swabs may be necessary when rectal infection is suspected or screening is indicated.

The appropriate specimen depends on the patient’s anatomy, exposure history and symptoms.

37. Chlamydia and Gonorrhoea Testing

Patients with suspected chlamydial infection are commonly tested for gonorrhoea at the same time.

This is because both organisms may cause urethritis and cervicitis.

Coinfection can occur.

Many modern molecular assays detect both Chlamydia trachomatis and Neisseria gonorrhoeae from the same specimen.

Identifying both infections is important because treatment regimens differ.

Treatment of Chlamydial Infection

38. Doxycycline

Doxycycline is the preferred treatment for uncomplicated chlamydial infection in non-pregnant adults and adolescents.

It belongs to the tetracycline class of antibiotics.

Doxycycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit.

This prevents aminoacyl-tRNA from attaching normally to the ribosome.

As a result, bacterial protein synthesis is inhibited.

Doxycycline is generally bacteriostatic.

39. Recommended Doxycycline Regimen

The commonly recommended adult regimen for uncomplicated urogenital chlamydial infection is:

Doxycycline 100 mg orally twice daily for seven days.

This regimen is effective for uncomplicated urethral, cervical and rectal chlamydial infection.

Doxycycline is particularly preferred for rectal infection because it has demonstrated better efficacy than single-dose azithromycin in relevant studies.

Patients should complete the prescribed course.

40. Erythromycin

Erythromycin is a macrolide antibiotic with activity against Chlamydia trachomatis.

It inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit.

This interferes with protein elongation.

The original notes correctly identify erythromycin as an antibiotic with activity against chlamydia.

However, erythromycin is no longer a preferred routine treatment for uncomplicated adult chlamydial infection because gastrointestinal adverse effects can reduce adherence and other regimens are generally better tolerated.

It remains relevant in selected situations, including some neonatal infections.

41. Azithromycin

Azithromycin is another macrolide antibiotic used in the treatment of chlamydial infection.

It binds to the 50S ribosomal subunit and inhibits bacterial protein synthesis.

A single oral dose of azithromycin 1 g is an alternative regimen for uncomplicated chlamydial infection in non-pregnant adults when doxycycline is unsuitable.

However, azithromycin is less effective than doxycycline for rectal chlamydial infection.

Therefore, doxycycline is generally preferred when appropriate.

42. Treatment During Pregnancy

Doxycycline is generally avoided during pregnancy, particularly in later pregnancy.

Azithromycin 1 g orally as a single dose is a recommended regimen for uncomplicated chlamydial infection during pregnancy.

Amoxicillin is an alternative in selected circumstances.

Pregnant patients should undergo appropriate follow-up testing because persistent infection can affect maternal and neonatal health.

A test of cure using NAAT is generally recommended approximately four weeks after treatment during pregnancy.

43. Treatment of Pelvic Inflammatory Disease

Chlamydia-associated PID requires broader antimicrobial treatment than uncomplicated cervical infection.

This is because PID may involve multiple organisms, including Neisseria gonorrhoeae and anaerobic bacteria.

A commonly recommended outpatient regimen includes ceftriaxone, doxycycline and metronidazole.

Doxycycline treats chlamydial infection, while ceftriaxone provides gonococcal coverage and metronidazole provides anaerobic coverage.

Severe PID, pregnancy, tubo-ovarian abscess or inability to tolerate oral treatment may require hospitalisation and intravenous antibiotics.

44. Treatment of Sexual Partners

Sexual partner management is essential to prevent reinfection.

Recent sexual partners should be assessed and treated according to applicable guidelines.

Patients should avoid sexual intercourse until they and their partners have completed appropriate treatment.

For a seven-day doxycycline regimen, this generally means abstaining until the course has been completed.

For single-dose treatment, patients should avoid sexual intercourse for seven days after treatment.

Reinfection is common when sexual partners remain untreated.

45. Follow-Up and Retesting

Routine test of cure is not generally necessary for non-pregnant patients with uncomplicated chlamydial infection who have completed appropriate treatment and have no persistent symptoms or concerns about adherence.

However, repeat testing is recommended approximately three months after treatment because reinfection is common.

Pregnant patients require a test of cure approximately four weeks after treatment.

NAAT should not be performed too soon after therapy because residual bacterial genetic material may produce a positive result even after successful treatment.

Complications of Chlamydial Infection

46. Female Infertility

Chlamydia may cause infertility through ascending infection and inflammation of the fallopian tubes.

Repeated or severe episodes of salpingitis increase the risk of tubal scarring.

This may impair ovum transport and fertilisation.

The resulting infertility may persist despite successful antibiotic treatment because established structural damage may be irreversible.

47. Ectopic Pregnancy

Tubal scarring following chlamydial infection increases the risk of ectopic pregnancy.

Impaired transport of the fertilised ovum may lead to implantation within the fallopian tube.

Tubal ectopic pregnancy can rupture and cause severe internal bleeding.

Early recognition of pregnancy-related pelvic pain is therefore important.

48. Chronic Pelvic Pain

Chlamydia-associated PID may result in persistent pelvic pain.

This may arise from adhesions, chronic inflammation or structural damage.

Pain can persist even after the original infection has been eradicated.

49. Neonatal Conjunctivitis

Maternal chlamydial infection may be transmitted during childbirth.

The infant may develop conjunctivitis approximately 5–12 days after birth.

Symptoms include conjunctival redness, eyelid swelling and mucopurulent discharge.

Systemic antibiotic treatment is required.

50. Neonatal Pneumonia

Neonatal chlamydial pneumonia typically develops between one and three months of age.

It classically produces an afebrile illness with a staccato cough and tachypnoea.

Chest imaging may demonstrate diffuse interstitial changes.

Prevention of Chlamydial Infection

51. Safer Sexual Practices

Chlamydial infection can be prevented by reducing exposure to infected genital secretions.

Consistent and correct condom use reduces the risk of transmission.

However, no barrier method provides complete protection against all sexually transmitted infections.

Avoiding sexual contact until treatment is completed is important in preventing reinfection.

52. Screening

Because chlamydial infection is frequently asymptomatic, screening is an important preventive strategy.

Screening recommendations vary according to age, sexual exposure, pregnancy status and local guidelines.

Sexually active younger women and other individuals at increased risk are commonly prioritised for screening.

Early detection and treatment can reduce transmission and prevent reproductive complications.

53. Antenatal Screening

Chlamydia screening during pregnancy helps identify maternal infection before delivery.

Appropriate antibiotic treatment reduces the risk of neonatal conjunctivitis and pneumonia.

Pregnant patients may require repeat testing according to risk factors and local recommendations.

Differential Diagnosis of Urethritis

54. Chlamydial Urethritis

Chlamydial urethritis is caused by Chlamydia trachomatis.

It commonly produces mild dysuria and scanty mucoid or mucopurulent urethral discharge.

Many patients are asymptomatic.

Diagnosis is established using NAAT.

Treatment generally involves doxycycline.

55. Gonococcal Urethritis

Gonococcal urethritis is caused by Neisseria gonorrhoeae.

It classically produces more prominent purulent urethral discharge and dysuria.

However, symptoms overlap with chlamydial urethritis.

Diagnosis is usually established using NAAT, with culture and susceptibility testing in selected circumstances.

Treatment commonly involves ceftriaxone.

56. Mycoplasma genitalium Urethritis

Mycoplasma genitalium is another important cause of non-gonococcal urethritis.

It may produce persistent or recurrent urethral symptoms.

The organism lacks a cell wall, making beta-lactam antibiotics ineffective.

Treatment is complicated by increasing antimicrobial resistance.

Resistance-guided therapy is preferred when available.

Important Corrections and Clarifications

57. Proportion of Non-Specific Urethritis Caused by Chlamydia

The original notes state that chlamydia causes more than 50% of cases of non-specific urethritis.

Although chlamydia is a major cause of NGU, this proportion is not consistently supported by modern epidemiological data.

The proportion varies by population, with estimates commonly around 15–40%.

Other organisms, particularly Mycoplasma genitalium, are also important causes.

58. Association with PID and Infertility

The original notes correctly identify chlamydia as an important cause of PID and infertility.

The main mechanism involves ascending infection, salpingitis and subsequent fallopian tube scarring.

This can lead to tubal infertility, ectopic pregnancy and chronic pelvic pain.

59. Neonatal Infection

The original notes correctly identify neonatal conjunctivitis and diffuse pneumonia as complications.

Chlamydial conjunctivitis typically develops within the first two weeks of life.

Chlamydial pneumonia usually develops between one and three months of age.

The pneumonia is classically afebrile and associated with a staccato cough.

60. Antibiotic Sensitivity

The original notes identify doxycycline and erythromycin as active against chlamydia.

Both have antimicrobial activity.

However, doxycycline is now preferred for uncomplicated chlamydial infection in non-pregnant adults.

Azithromycin is recommended during pregnancy, while erythromycin remains relevant in selected circumstances, particularly neonatal treatment.

Important Clinical Associations – Note Form

61. Chlamydia trachomatis

Chlamydia trachomatis is an obligate intracellular bacterium.

It infects epithelial cells of the genitourinary tract, conjunctiva and other mucosal surfaces.

It has a distinctive developmental cycle involving elementary and reticulate bodies.

62. Elementary Body

The elementary body is the infectious extracellular form.

It attaches to and enters susceptible host cells.

63. Reticulate Body

The reticulate body is the metabolically active intracellular replicative form.

It multiplies within membrane-bound inclusions.

64. Non-Gonococcal Urethritis

Chlamydia is a major cause of non-gonococcal urethritis.

Patients may develop dysuria and scanty urethral discharge.

Many infections are asymptomatic.

65. Pelvic Inflammatory Disease

Chlamydia may ascend from the cervix into the upper genital tract.

This can cause endometritis, salpingitis and PID.

66. Tubal Infertility

Repeated or severe chlamydial salpingitis may produce fallopian tube scarring.

This can impair fertilisation and increase the risk of infertility.

67. Ectopic Pregnancy

Tubal damage may interfere with normal transport of the fertilised ovum.

This increases the risk of implantation within the fallopian tube.

68. Neonatal Conjunctivitis

Chlamydial conjunctivitis typically develops 5–12 days after birth.

It produces conjunctival inflammation and mucopurulent discharge.

69. Neonatal Pneumonia

Chlamydial pneumonia typically develops at 1–3 months of age.

It is classically afebrile and associated with a staccato cough.

70. Doxycycline

Doxycycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit.

It is the preferred treatment for uncomplicated chlamydial infection in non-pregnant adults.

71. Erythromycin

Erythromycin is a macrolide antibiotic that inhibits the 50S ribosomal subunit.

It is active against chlamydia but is no longer preferred for routine uncomplicated adult infection.

It remains useful in selected neonatal infections.

72. Azithromycin

Azithromycin is a macrolide antibiotic.

It is a recommended treatment for chlamydial infection during pregnancy.

It may also be used as an alternative in selected non-pregnant patients.

Key Clinical Pattern

The defining characteristic of chlamydial infection is its ability to cause frequently asymptomatic genital infection that may progress to urethritis, cervicitis, PID and infertility, or be transmitted to neonates during childbirth.

Chlamydia trachomatis → Obligate intracellular bacterium.

Elementary body → Infectious extracellular form.

Reticulate body → Intracellular replicative form.

Serovars D–K → Urogenital infection, neonatal conjunctivitis and neonatal pneumonia.

Serovars A–C → Trachoma.

Serovars L1–L3 → Lymphogranuloma venereum.

Men → Non-gonococcal urethritis, often with mild discharge and dysuria.

Women → Cervicitis and ascending pelvic inflammatory disease.

PID → Salpingitis, tubal damage, infertility and ectopic pregnancy.

Neonatal conjunctivitis → Develops approximately 5–12 days after birth.

Neonatal pneumonia → Afebrile pneumonia with staccato cough at 1–3 months of age.

Reactive arthritis → May follow chlamydial genitourinary infection.

Fitz-Hugh–Curtis syndrome → Perihepatitis associated with PID.

NAAT → Preferred diagnostic test.

Doxycycline → First-line treatment in non-pregnant adults.

Azithromycin → Recommended treatment during pregnancy.

Erythromycin → Active against chlamydia and used in selected neonatal infections.

Partner treatment → Important for preventing reinfection.

For examinations, remember the classical association: Chlamydia trachomatis causes non-gonococcal urethritis in men, pelvic inflammatory disease and tubal infertility in women, and conjunctivitis or afebrile staccato-cough pneumonia in neonates. Doxycycline is the preferred treatment for uncomplicated infection in non-pregnant adults.

Medicine – Trichomoniasis: Aetiology, Transmission, Pathogenesis, Clinical Features, Diagnosis and Treatment

1. Introduction to Trichomoniasis

Trichomoniasis is a common sexually transmitted infection (STI) caused by Trichomonas vaginalis, a motile, flagellated protozoan parasite.

The infection primarily affects the lower genitourinary tract and is an important cause of vaginitis and abnormal vaginal discharge.

In women, trichomoniasis may produce a characteristic frothy, yellow-green, foul-smelling vaginal discharge, accompanied by vulval irritation, itching and inflammation.

In men, infection is frequently asymptomatic, although urethritis and other genitourinary symptoms may occasionally occur.

An important feature of trichomoniasis is that many infected individuals have no symptoms but can still transmit the parasite to sexual partners.

The infection is treatable with nitroimidazole antibiotics, particularly metronidazole, and management of sexual partners is essential to reduce reinfection.

2. Aetiological Agent – Trichomonas vaginalis

The causative organism is Trichomonas vaginalis, a unicellular protozoan parasite.

Unlike bacterial sexually transmitted infections such as gonorrhoea and chlamydia, trichomoniasis is caused by a eukaryotic microorganism.

Trichomonas vaginalis is a pear-shaped, flagellated protozoan that uses its flagella and undulating membrane for movement.

The organism exists predominantly in the trophozoite form and does not have a recognised cyst stage.

Its motility is an important characteristic that can be observed during microscopic examination of a fresh clinical specimen.

The parasite primarily inhabits the vagina, urethra and other parts of the lower genitourinary tract.

3. Morphological Characteristics

Trichomonas vaginalis is typically pear-shaped or oval.

It possesses four anterior flagella and an additional recurrent flagellum associated with an undulating membrane.

These structures allow the organism to move rapidly through genital secretions.

It also contains an axostyle, a supporting structure that extends through the body of the parasite.

Under wet-mount microscopy, the organism may demonstrate characteristic jerky or twitching movements.

This motility is a useful diagnostic feature, although microscopy is less sensitive than modern molecular tests.

4. Transmission of Trichomoniasis

Trichomoniasis is transmitted predominantly through sexual contact.

Transmission usually occurs when infected genital secretions come into contact with susceptible mucosal surfaces during sexual activity.

The parasite can spread between sexual partners even when the infected individual has no symptoms.

Transmission is most commonly associated with genital sexual contact.

Unlike some other sexually transmitted infections, Trichomonas vaginalis primarily infects the lower genitourinary tract rather than the bloodstream or distant organs.

Because asymptomatic infection is common, untreated sexual partners can act as reservoirs for continued transmission.

5. Incubation Period

The incubation period of symptomatic trichomoniasis is generally approximately 5–28 days following exposure.

However, many infected individuals remain asymptomatic.

Some patients may develop symptoms only after a prolonged period of infection.

Therefore, the onset of symptoms does not reliably establish the exact timing of acquisition.

Persistent infection can continue for months or longer without appropriate treatment.

Pathogenesis of Trichomoniasis

6. Colonisation of the Genitourinary Tract

Following transmission, Trichomonas vaginalis colonises the epithelial surfaces of the lower genitourinary tract.

In women, the parasite commonly infects the vagina and may also involve the urethra and cervix.

In men, infection most commonly involves the urethra.

The organism adheres to epithelial cells and interacts with the local mucosal environment.

This attachment allows the parasite to persist and contribute to epithelial injury.

7. Development of Vaginal Inflammation

Trichomonas vaginalis causes inflammation through direct interactions with epithelial cells and the host immune response.

The parasite can damage epithelial surfaces and stimulate the release of inflammatory mediators.

This produces redness, swelling and irritation of the vaginal mucosa.

Inflammation also increases vaginal secretions, contributing to abnormal discharge.

The severity of inflammation varies considerably between individuals.

Some patients develop pronounced vaginitis, while others remain asymptomatic despite infection.

8. Changes in Vaginal pH

The normal vaginal environment is generally acidic, with a pH commonly between approximately 3.8 and 4.5 during reproductive years.

This acidic environment is maintained largely by lactobacilli.

Trichomoniasis is commonly associated with an increase in vaginal pH.

Affected patients often have a vaginal pH greater than 4.5.

However, elevated vaginal pH is not specific to trichomoniasis and may also occur in bacterial vaginosis.

Therefore, pH measurement is a supportive finding rather than a definitive diagnostic test.

Clinical Features of Trichomoniasis in Women

9. Vaginal Discharge

The classical presentation of trichomoniasis is abnormal vaginal discharge.

The discharge is traditionally described as yellow-green, frothy and foul-smelling.

It may be relatively thin or abundant.

The unpleasant odour is associated with changes in the vaginal environment and inflammatory secretions.

However, not all patients develop the classical discharge.

Some women have white, grey or yellow discharge, while others have minimal or no noticeable abnormalities.

Therefore, the absence of green or frothy discharge does not exclude trichomoniasis.

10. Vaginitis

Vaginitis refers to inflammation of the vaginal mucosa.

In trichomoniasis, the vaginal epithelium may become erythematous and irritated.

Patients may experience burning, discomfort and increased sensitivity.

Inflammation can produce pain during sexual intercourse and irritation during urination.

Vaginitis may be accompanied by vulval inflammation, producing vulvovaginitis.

The severity ranges from mild irritation to marked inflammation with significant discomfort.

11. Vulval Pruritus

Vulval itching is a common symptom of symptomatic trichomoniasis.

It results from local inflammation and irritation of the vulval tissues.

Patients may experience persistent itching, burning or soreness.

Scratching may produce secondary excoriations and further irritation.

However, vulval pruritus is not specific to trichomoniasis and may also occur in vulvovaginal candidiasis, dermatitis and other genital conditions.

12. Dysuria

Dysuria refers to pain or burning during urination.

Trichomoniasis may produce dysuria because the parasite can infect or irritate the urethral epithelium.

Inflammation of the external genital tissues may also cause discomfort when urine contacts irritated mucosal surfaces.

Patients may therefore present with urinary symptoms despite the absence of a conventional bacterial urinary tract infection.

13. Dyspareunia

Dyspareunia refers to pain during sexual intercourse.

In trichomoniasis, dyspareunia may result from inflammation of the vaginal and vulval mucosa.

The discomfort may be superficial and associated with local irritation.

Some patients may also experience postcoital spotting because inflamed cervical or vaginal tissue can bleed more easily.

Persistent dyspareunia requires assessment for other gynaecological and infectious causes.

14. Strawberry Cervix

A classical examination finding in trichomoniasis is the strawberry cervix, also called colpitis macularis.

This appearance results from punctate haemorrhages and inflammatory changes involving the cervical mucosa.

The cervix may show multiple small red spots against an inflamed background.

These petechial lesions produce an appearance resembling the surface of a strawberry.

Although strawberry cervix is a characteristic association, it is not present in most cases on routine examination.

It may be more readily detected using colposcopy.

Therefore, the absence of a strawberry cervix does not exclude trichomoniasis.

15. Asymptomatic Infection in Women

A substantial proportion of women with trichomoniasis have no noticeable symptoms.

These individuals may still carry the parasite within the lower genital tract.

Asymptomatic infection can persist for prolonged periods.

Despite the absence of symptoms, transmission to sexual partners remains possible.

This is one reason trichomoniasis can continue circulating within sexually active populations.

Clinical Features of Trichomoniasis in Men

16. Asymptomatic Infection

Trichomoniasis is frequently asymptomatic in men.

The organism may colonise the urethra without producing significant inflammation.

Asymptomatic individuals may unknowingly transmit the infection to sexual partners.

Therefore, the absence of urethral symptoms does not exclude infection.

17. Urethritis

When symptomatic, trichomoniasis in men may cause urethritis.

Urethritis is inflammation of the urethral mucosa.

Patients may develop burning during urination, urethral irritation or a small amount of urethral discharge.

The discharge is usually less prominent than the vaginal discharge seen in symptomatic women.

Because these symptoms overlap with gonorrhoea and chlamydia, laboratory testing is important.

18. Other Genitourinary Manifestations

Trichomoniasis may occasionally be associated with irritation of the glans penis or other lower genitourinary symptoms.

Prostatic involvement has also been described, although its clinical significance varies.

Most infected men do not develop severe disease.

Nevertheless, untreated infection can contribute to ongoing transmission and reinfection of sexual partners.

Diagnosis of Trichomoniasis

19. Clinical Suspicion

Trichomoniasis should be considered in patients presenting with abnormal vaginal discharge, vaginal irritation, vulval itching or dysuria.

The combination of frothy yellow-green discharge, elevated vaginal pH and cervical inflammation is suggestive.

However, these findings are not sufficiently specific to establish the diagnosis.

Other conditions, particularly bacterial vaginosis and vulvovaginal candidiasis, can produce overlapping symptoms.

Laboratory testing is therefore important.

20. Wet-Mount Microscopy

Wet-mount microscopy is a traditional diagnostic method for trichomoniasis.

A sample of vaginal secretions is mixed with saline and examined under a microscope.

The presence of motile, flagellated Trichomonas vaginalis trophozoites supports the diagnosis.

The organisms may demonstrate characteristic jerky or twitching movement.

However, wet-mount microscopy has relatively low sensitivity compared with molecular tests.

Its sensitivity also decreases if the specimen is not examined promptly because trophozoite motility diminishes over time.

A negative wet mount therefore does not exclude trichomoniasis.

21. Nucleic Acid Amplification Testing

Nucleic acid amplification tests (NAATs) are the preferred diagnostic tests for trichomoniasis when available.

These tests detect genetic material from Trichomonas vaginalis.

They are considerably more sensitive than conventional wet-mount microscopy.

Depending on the assay, specimens may include vaginal swabs, endocervical samples or urine.

Appropriate specimen selection depends on the patient’s anatomy and the validated test.

NAATs are particularly useful when symptoms are suggestive but microscopy is negative.

22. Vaginal pH Testing

Trichomoniasis is commonly associated with a vaginal pH above 4.5.

This finding reflects disruption of the normal acidic vaginal environment.

However, elevated pH also occurs in bacterial vaginosis.

In contrast, uncomplicated vulvovaginal candidiasis usually occurs with a normal vaginal pH.

Vaginal pH is therefore useful in the differential diagnosis of vaginal discharge but cannot independently confirm trichomoniasis.

23. Culture

Culture methods can be used to detect Trichomonas vaginalis.

They involve placing clinical specimens into specialised media that support parasite growth.

Culture was historically an important diagnostic technique.

However, modern NAATs generally provide superior sensitivity and are more widely preferred when available.

Culture may still have a role in selected circumstances, including specialised investigations.

Treatment of Trichomoniasis

24. Metronidazole

Metronidazole is a first-line treatment for trichomoniasis.

It belongs to the nitroimidazole class of antimicrobial drugs.

Metronidazole enters susceptible microorganisms and undergoes intracellular reduction.

This produces reactive compounds that damage microbial DNA and interfere with nucleic acid synthesis.

The resulting DNA injury inhibits parasite survival and replication.

Metronidazole is active against Trichomonas vaginalis and several anaerobic microorganisms.

25. Recommended Treatment in Women

For women, a commonly recommended regimen is metronidazole 500 mg orally twice daily for seven days.

This multidose regimen is preferred over a single 2 g dose in current CDC guidance for women because it provides better treatment outcomes.

The medication should be taken as prescribed, even if symptoms improve before the course is completed.

Treatment is important because untreated infection may persist and contribute to further transmission.

The precise regimen should follow applicable local clinical guidelines.

26. Recommended Treatment in Men

For men, a commonly recommended regimen is metronidazole 2 g orally as a single dose.

This is the standard regimen in CDC guidance for uncomplicated trichomoniasis in men.

Alternative regimens may be considered according to clinical circumstances and local guidance.

Treatment is important even when symptoms are absent, particularly when a sexual partner has confirmed infection.

27. Tinidazole

Tinidazole is another nitroimidazole antimicrobial agent active against Trichomonas vaginalis.

It has a similar mechanism of action to metronidazole.

A commonly used alternative regimen is tinidazole 2 g orally as a single dose.

Tinidazole may be considered when clinically appropriate, including selected cases of persistent infection.

However, treatment selection depends on pregnancy status, tolerability, availability and relevant guidelines.

28. Treatment of Sexual Partners

Treatment of sexual partners is an essential component of trichomoniasis management.

Sexual partners may carry Trichomonas vaginalis without symptoms.

If only one partner is treated, reinfection can occur after sexual contact resumes.

Therefore, current sexual partners should receive appropriate treatment according to clinical guidance.

Patients should avoid sexual intercourse until they and their partners have completed treatment and symptoms have resolved.

This helps reduce reinfection and ongoing transmission.

29. Persistent or Recurrent Trichomoniasis

Trichomoniasis may persist or recur after treatment.

A common cause is reinfection from an untreated sexual partner.

Other causes include incomplete adherence to medication and, less commonly, antimicrobial resistance.

Patients with persistent symptoms should be reassessed for reinfection, treatment adherence and alternative diagnoses.

When repeat molecular testing is used after treatment, timing matters because residual nucleic acid may remain detectable temporarily.

In women, routine retesting approximately three months after treatment is recommended in CDC guidance because reinfection is common.

30. Adverse Effects of Metronidazole

Metronidazole is generally well tolerated.

Common adverse effects include nausea, abdominal discomfort, headache and a metallic taste.

Occasionally, patients may experience dizziness or gastrointestinal upset.

Rare adverse effects include peripheral neuropathy, particularly with prolonged or repeated exposure.

Metronidazole may interact with certain medications, including warfarin.

Patients should follow the prescribed regimen and seek medical advice if significant adverse effects occur.

Trichomoniasis During Pregnancy

31. Clinical Importance

Trichomoniasis during pregnancy is associated with adverse pregnancy outcomes.

These may include premature rupture of membranes, preterm delivery and low birth weight.

However, an association does not mean that every infected pregnant patient will experience complications.

Symptomatic pregnant patients should be evaluated and treated appropriately.

Metronidazole is generally considered safe for use during pregnancy when indicated.

32. Treatment During Pregnancy

Metronidazole is the recommended treatment for symptomatic trichomoniasis during pregnancy.

The seven-day oral regimen is commonly used.

Available evidence indicates that metronidazole poses a low risk to the developing fetus.

Tinidazole is generally avoided during pregnancy because human safety data are limited.

Treatment decisions should consider the patient’s symptoms, pregnancy stage and applicable obstetric guidance.

Complications of Trichomoniasis

33. Persistent Vaginal Inflammation

Untreated trichomoniasis can produce persistent inflammation of the vaginal mucosa.

Patients may experience recurrent discharge, irritation and discomfort.

Chronic inflammation may interfere with sexual activity and quality of life.

Persistent symptoms also increase the likelihood of repeated healthcare visits and antimicrobial treatment.

34. Increased Susceptibility to HIV

Trichomoniasis is associated with an increased risk of HIV acquisition.

Inflammation of the genital mucosa may disrupt epithelial barriers and recruit immune cells that are susceptible to HIV infection.

This can facilitate viral transmission during sexual exposure.

Trichomoniasis may also increase genital HIV shedding in individuals living with HIV.

Appropriate diagnosis and treatment are therefore important components of sexual health care.

35. Adverse Pregnancy Outcomes

Maternal trichomoniasis has been associated with preterm delivery, premature rupture of membranes and low birth weight.

The mechanisms may involve local genital inflammation and alterations in the reproductive tract environment.

Treatment of symptomatic infection is recommended, although treatment does not guarantee prevention of every associated pregnancy complication.

Differential Diagnosis of Vaginal Discharge

36. Trichomoniasis

Trichomoniasis is caused by the flagellated protozoan Trichomonas vaginalis.

The classical discharge is frothy, yellow-green and foul-smelling.

Vaginal pH is commonly above 4.5.

Patients may experience itching, dysuria and dyspareunia.

A strawberry cervix may occasionally be present.

Treatment involves oral metronidazole or an appropriate alternative.

37. Bacterial Vaginosis

Bacterial vaginosis is associated with disruption of normal vaginal microbiota and a reduction in protective lactobacilli.

It commonly produces a thin, homogeneous, grey-white discharge with a fishy odour.

Vaginal pH is typically above 4.5.

Microscopy may reveal clue cells, which are vaginal epithelial cells coated with bacteria.

Bacterial vaginosis is not caused by Trichomonas vaginalis.

Metronidazole is also used in its treatment, but routine partner treatment is not generally recommended in the same way as for trichomoniasis.

38. Vulvovaginal Candidiasis

Vulvovaginal candidiasis is most commonly caused by Candida albicans.

It typically produces thick, white, curd-like vaginal discharge.

Marked vulval itching and irritation are common.

The discharge is usually not strongly malodorous.

Vaginal pH generally remains within the normal acidic range.

Treatment involves antifungal medication, such as topical clotrimazole or oral fluconazole in appropriate non-pregnant patients.

39. Important Examination Distinction

The three classical causes of abnormal vaginal discharge have different characteristic features.

Trichomoniasis → Frothy, yellow-green, foul-smelling discharge with possible strawberry cervix.

Bacterial vaginosis → Thin, grey-white discharge with fishy odour and clue cells.

Vulvovaginal candidiasis → Thick, white, curd-like discharge with prominent itching.

These patterns are useful for examinations, but clinical appearances overlap and laboratory testing may be necessary.

Prevention of Trichomoniasis

40. Safer Sexual Practices

Trichomoniasis can be prevented by reducing exposure to infected genital secretions.

Consistent and correct condom use reduces transmission risk.

However, condoms do not eliminate the risk of all sexually transmitted infections.

Patients with confirmed infection should avoid sexual activity until treatment has been completed by themselves and their partners.

41. Screening for Other Sexually Transmitted Infections

Patients diagnosed with trichomoniasis should be assessed for other sexually transmitted infections when appropriate.

Testing may include HIV, syphilis, gonorrhoea and chlamydia.

This is important because different sexually transmitted infections may coexist.

Identifying and treating associated infections helps prevent complications and further transmission.

Important Corrections and Clarifications

42. Causative Organism

The original notes correctly identify Trichomonas vaginalis as the cause of trichomoniasis.

It is a flagellated protozoan parasite rather than a bacterium or fungus.

The organism exists as a motile trophozoite and does not have a recognised cyst stage.

43. Characteristic Vaginal Discharge

The original notes correctly describe foul-smelling, greenish-yellow vaginal discharge as a characteristic feature.

The discharge may also be frothy.

However, this appearance is not present in every patient.

Many infected individuals have mild symptoms or remain asymptomatic.

44. Vaginitis

Trichomoniasis is an important cause of infectious vaginitis.

It produces inflammation of the vaginal mucosa, leading to irritation, itching, burning and sometimes dyspareunia.

A strawberry cervix is a classical but relatively uncommon finding.

45. Treatment with Metronidazole

The original notes correctly identify metronidazole as a treatment for trichomoniasis.

For women, the preferred CDC regimen is oral metronidazole 500 mg twice daily for seven days.

For men, oral metronidazole 2 g as a single dose is commonly recommended.

Sexual partners should also be treated to prevent reinfection.

Important Clinical Associations – Note Form

46. Trichomonas vaginalis

Trichomonas vaginalis is a motile, flagellated protozoan parasite.

It causes a sexually transmitted infection primarily affecting the lower genitourinary tract.

It exists in the trophozoite form without a recognised cyst stage.

47. Vaginal Discharge

The classical discharge is frothy, yellow-green and foul-smelling.

However, the appearance is variable, and some patients have minimal discharge.

48. Strawberry Cervix

Strawberry cervix refers to punctate cervical haemorrhages associated with inflammation.

It is a classical examination finding in trichomoniasis but is not present in most cases.

49. Vaginal pH

Trichomoniasis commonly increases vaginal pH above 4.5.

An elevated pH supports the diagnosis but is not specific.

Bacterial vaginosis may produce a similar pH change.

50. Wet-Mount Microscopy

Wet-mount microscopy may demonstrate motile, flagellated trophozoites.

The organisms show characteristic jerky movements.

However, microscopy has limited sensitivity compared with NAATs.

51. NAAT Testing

Nucleic acid amplification testing is the preferred diagnostic approach when available.

It detects Trichomonas vaginalis genetic material with high sensitivity.

52. Metronidazole

Metronidazole is a nitroimidazole antimicrobial drug.

It damages microbial DNA following intracellular activation.

It is a first-line treatment for trichomoniasis.

53. Partner Treatment

Sexual partners should receive appropriate treatment because asymptomatic infection is common.

Treating partners reduces reinfection and continued transmission.

Key Clinical Pattern

The defining feature of trichomoniasis is infectious vaginitis caused by the flagellated protozoan Trichomonas vaginalis, classically producing frothy, yellow-green, foul-smelling vaginal discharge.

Trichomonas vaginalis → Flagellated protozoan parasite.

Transmission → Predominantly sexual contact.

Typical vaginal discharge → Frothy, yellow-green and foul-smelling.

Vaginitis → Vaginal inflammation, itching, irritation and burning.

Strawberry cervix → Punctate cervical haemorrhages.

Vaginal pH → Usually greater than 4.5.

Wet-mount microscopy → Motile, flagellated trophozoites.

NAAT → Preferred diagnostic test when available.

Metronidazole → First-line treatment.

Women → Metronidazole 500 mg orally twice daily for seven days.

Men → Metronidazole 2 g orally as a single dose.

Sexual partners → Require treatment to reduce reinfection.

Asymptomatic infection → Common, particularly in men.

HIV association → Genital inflammation may increase susceptibility to HIV acquisition.

For examinations, remember the classical association: Trichomonas vaginalis causes frothy, foul-smelling, yellow-green vaginal discharge, may produce a strawberry cervix, and is treated with oral metronidazole.

Medicine – Herpes Simplex Virus (HSV): Types, Transmission, Pathogenesis, Clinical Features, Diagnosis and Treatment

1. Introduction to Herpes Simplex Virus

Herpes simplex virus (HSV) is a common viral pathogen responsible for recurrent infections involving the skin, mucous membranes and occasionally the central nervous system.

HSV infection is particularly important in sexually transmitted infections because it is a major cause of painful genital ulceration.

There are two principal types of herpes simplex virus: HSV type 1 (HSV-1) and HSV type 2 (HSV-2). Although HSV-1 is traditionally associated with oral infections and HSV-2 with genital infections, both types can infect either anatomical region.

An important characteristic of HSV is its ability to establish lifelong latent infection within sensory nerve ganglia. Following the initial infection, the virus may remain dormant for months or years before becoming reactivated.

Reactivation may produce recurrent lesions, although these episodes are generally shorter and less severe than the initial symptomatic infection.

Antiviral medications such as aciclovir can reduce the duration and severity of symptoms, but they do not eradicate the latent virus.

2. Classification of Herpes Simplex Virus

Herpes simplex viruses belong to the family Herpesviridae, specifically the alphaherpesvirus subfamily.

They are enveloped viruses containing double-stranded DNA.

The two major types are HSV-1 and HSV-2.

Both types share several biological characteristics, including epithelial infection, neuronal latency and the ability to reactivate after periods of dormancy.

However, they differ in their usual anatomical distribution and patterns of recurrence.

3. Herpes Simplex Virus Type 1 (HSV-1)

HSV-1 is traditionally associated with infections involving the oral cavity, lips and surrounding facial skin.

The most familiar manifestation is herpes labialis, commonly called a cold sore.

HSV-1 may also cause primary gingivostomatitis, keratitis, encephalitis and genital herpes.

Genital HSV-1 infection has become an important cause of genital herpes, particularly following oral-genital sexual contact.

Compared with genital HSV-2 infection, genital HSV-1 generally produces fewer symptomatic recurrences and less frequent genital viral shedding.

However, recurrence patterns vary between individuals.

4. Herpes Simplex Virus Type 2 (HSV-2)

HSV-2 is predominantly associated with genital and anogenital infections.

It is transmitted mainly through sexual contact involving infected genital or perianal skin and mucous membranes.

HSV-2 commonly produces painful genital vesicles and ulcers.

Following primary infection, HSV-2 establishes latency within the sacral sensory ganglia.

Reactivation may produce recurrent genital lesions.

Genital HSV-2 infection generally causes more frequent recurrences and asymptomatic genital viral shedding than genital HSV-1 infection.

5. Transmission of Herpes Simplex Virus

HSV is transmitted through direct contact with infected skin, mucous membranes or secretions.

HSV-1 is commonly acquired through oral contact, including kissing, while HSV-2 is more commonly transmitted through sexual contact.

Both types can be transmitted during oral, vaginal or anal sexual activity.

Transmission is particularly likely when active vesicles or ulcers are present because these lesions contain infectious virus.

However, HSV can also be transmitted when no visible lesions are present.

This occurs because of asymptomatic viral shedding from infected epithelial surfaces.

Consequently, the absence of genital ulcers does not completely eliminate the possibility of HSV transmission.

6. Incubation Period

The incubation period for symptomatic HSV infection is generally approximately 2–12 days following exposure.

During this period, the virus replicates locally within epithelial cells.

The infected individual may subsequently develop vesicles, ulcers and regional lymphadenopathy.

However, many HSV infections are asymptomatic or produce symptoms so mild that they are not recognised.

Some individuals therefore remain unaware of their infection until a later symptomatic episode occurs.

Pathogenesis of HSV Infection

7. Entry into Epithelial Cells

HSV enters the body through mucous membranes or microscopic breaks in the skin.

The virus attaches to susceptible epithelial cells and introduces its genetic material into the host cell.

Viral replication occurs within the infected epithelial tissue.

This produces cellular injury and destruction, resulting in the formation of characteristic vesicular lesions.

The vesicles contain fluid and infectious viral particles.

When they rupture, they leave painful superficial ulcers.

8. Formation of Vesicles and Ulcers

HSV infection causes local epithelial cell destruction and inflammation.

Initially, small erythematous papules may appear at the affected site.

These subsequently develop into grouped, fluid-filled vesicles.

The vesicles are often fragile and rupture rapidly, especially on mucosal surfaces.

Their rupture produces shallow, painful ulcers with erythematous bases.

Several small ulcers may merge into larger irregular lesions.

The classical clinical association is multiple painful genital vesicles that rupture to form shallow ulcers.

9. Establishment of Viral Latency

One of the most important biological properties of HSV is its ability to establish lifelong latency.

Following initial epithelial infection, viral particles enter sensory nerve endings.

The virus travels through the sensory axons toward the neuronal cell bodies by retrograde axonal transport.

HSV then establishes latent infection within sensory ganglia.

During latency, the viral genome persists within neurons without producing the full cycle of infectious viral replication.

The immune system controls active viral replication but does not completely eliminate the latent viral genome.

This explains why HSV infection may persist for life.

10. Sites of HSV Latency

HSV-1 classically establishes latency within the trigeminal ganglion, particularly following oral or facial infection.

This explains why recurrent HSV-1 infection commonly produces cold sores around the lips.

HSV-2 classically establishes latency within the sacral sensory ganglia, particularly following genital infection.

This explains why recurrent HSV-2 infection commonly affects the genital and perianal regions.

However, the location of latency depends on the anatomical site of infection rather than the viral type alone.

Genital HSV-1 can also establish latency in sacral sensory ganglia.

11. Reactivation of Latent HSV

Latent HSV may reactivate after prolonged periods without symptoms.

Reactivation involves renewed viral replication within sensory neurons.

The virus travels from the ganglion toward the skin or mucous membrane through anterograde axonal transport.

It may then replicate within epithelial cells and produce recurrent vesicles or ulcers.

Reactivation can also result in asymptomatic viral shedding without visible lesions.

Therefore, recurrent infection may occur even after years of apparent dormancy.

12. Factors Associated with HSV Reactivation

Several physiological and environmental factors may be associated with HSV reactivation.

These include febrile illnesses, psychological stress, local trauma, ultraviolet light exposure and immunosuppression.

Menstruation may also be associated with recurrent episodes in some individuals.

However, many recurrences occur without an identifiable trigger.

The frequency of reactivation varies considerably between patients and generally decreases over time.

Clinical Features of Genital Herpes

13. Primary Genital Herpes

Primary genital herpes refers to the first episode of genital HSV infection in an individual without pre-existing antibodies to either HSV type.

It may produce a relatively severe clinical illness.

Patients can develop multiple painful vesicles and ulcers involving the genital or perianal region.

The lesions are often accompanied by local inflammation, tenderness and swelling.

Systemic symptoms may include fever, malaise, headache and muscle aches.

Primary infection may also produce tender inguinal lymphadenopathy.

However, many primary HSV infections are mild or asymptomatic.

14. Painful Genital Ulceration

Painful genital ulceration is the hallmark of symptomatic genital herpes.

The lesions commonly begin as clusters of small vesicles on an erythematous base.

These vesicles rupture and form shallow ulcers.

The ulcers may be particularly painful when they occur on sensitive genital mucosal surfaces.

Patients may experience burning, stinging or discomfort during movement and sexual intercourse.

The lesions usually heal without significant scarring in immunocompetent individuals.

15. Genital Herpes in Men

In men, genital herpes may involve the glans penis, foreskin, penile shaft, scrotum, perineum or perianal region.

The lesions may appear as grouped vesicles or painful superficial ulcers.

Patients may complain of genital pain, burning or irritation.

Tender inguinal lymphadenopathy may occur during the first episode.

Occasionally, extensive inflammation can make urination uncomfortable.

16. Genital Herpes in Women

In women, genital herpes may involve the vulva, labia, vaginal opening, vagina, cervix, perineum or perianal region.

Painful vesicles and ulcers may develop on external genital skin or mucosal surfaces.

Dysuria is common when urine contacts inflamed or ulcerated tissue.

Some patients experience significant vulval swelling and discomfort.

Cervical involvement may produce cervicitis or abnormal vaginal discharge.

Severe first episodes can occasionally cause urinary retention because of pain or sacral nerve involvement.

17. Systemic Symptoms

The first symptomatic episode of genital herpes may be accompanied by constitutional symptoms.

These include fever, malaise, fatigue, headache and generalised muscle aches.

Regional lymphadenopathy is also common.

Systemic symptoms are generally more pronounced during primary infection than during recurrent episodes.

However, the severity of the first recognised episode depends on the patient’s previous HSV exposure and immune response.

18. Prodromal Symptoms

Some patients experience prodromal symptoms shortly before recurrent lesions appear.

These may include tingling, itching, burning or localised pain in the genital or perianal region.

The prodrome reflects viral reactivation and early local nerve or epithelial involvement.

Lesions may develop within hours or a short period after the onset of these symptoms.

Recognition of the prodrome is clinically useful because episodic antiviral treatment is most effective when started early.

Recurrent Genital Herpes

19. Why Genital Herpes Recurs

Genital herpes recurs because HSV remains latent within sensory nerve ganglia.

The immune system suppresses viral replication but does not eliminate the latent viral genome.

When reactivation occurs, the virus travels along sensory nerves to the epithelial surface.

This may produce new vesicles or ulcers at or near the original site of infection.

The frequency of recurrence varies between individuals.

Some patients experience frequent episodes, whereas others have only occasional recurrences or none at all.

20. Clinical Features of Recurrent Genital Herpes

Recurrent genital herpes generally produces less severe symptoms than the initial symptomatic episode.

The lesions are usually fewer in number and more localised.

Systemic symptoms such as fever and malaise are less common.

Healing is typically faster than during primary infection.

Some patients experience only mild tingling, burning or a few small ulcers.

However, recurrent episodes can still be painful and distressing.

21. Differences Between HSV-1 and HSV-2 Recurrence

Genital HSV-2 infection generally causes more frequent symptomatic recurrences than genital HSV-1 infection.

HSV-2 is also associated with more frequent asymptomatic genital viral shedding.

Genital HSV-1 typically recurs less often, particularly after the first year of infection.

This difference is important when counselling patients about the expected natural history of genital herpes.

Nevertheless, individual recurrence patterns vary considerably.

22. Asymptomatic Viral Shedding

HSV can be released from infected genital skin or mucous membranes without producing visible ulcers or vesicles.

This is called asymptomatic viral shedding.

During these periods, infectious virus may be present even though the patient feels entirely well.

Asymptomatic shedding is an important mechanism of genital herpes transmission.

It explains why HSV can spread between sexual partners in the absence of recognised outbreaks.

Suppressive antiviral therapy can reduce viral shedding, although it does not eliminate transmission risk completely.

Other Clinical Manifestations of HSV

23. Herpes Labialis

Herpes labialis is a common manifestation of HSV-1 infection.

It typically produces recurrent clusters of painful vesicles around the lips or oral commissures.

Patients may experience tingling or burning before the lesions appear.

The vesicles rupture, crust and gradually heal.

Reactivation may be associated with febrile illness, ultraviolet exposure or other physiological stresses.

24. Herpetic Gingivostomatitis

Primary HSV-1 infection may cause acute gingivostomatitis, particularly in children.

The condition produces painful oral vesicles and ulcers, gingival inflammation and difficulty eating or drinking.

Fever, irritability and cervical lymphadenopathy may occur.

Severe oral discomfort can lead to dehydration.

Management focuses on adequate hydration, analgesia and antiviral treatment in selected cases.

25. Herpetic Keratitis

HSV may infect the cornea and produce herpetic keratitis.

A characteristic manifestation is dendritic corneal ulceration, which may be demonstrated using fluorescein staining.

Patients may experience eye pain, redness, photophobia, tearing and blurred vision.

Recurrent infection can produce corneal scarring and visual impairment.

Suspected herpetic keratitis requires prompt ophthalmological assessment.

Topical corticosteroids should not be used without specialist guidance because they can worsen active epithelial HSV keratitis.

26. Herpes Simplex Encephalitis

HSV-1 is an important cause of sporadic viral encephalitis.

The infection classically involves the temporal lobes and may produce haemorrhagic necrosis.

Patients may present with fever, headache, altered consciousness, behavioural changes, seizures or focal neurological deficits.

Diagnosis commonly involves cerebrospinal fluid HSV PCR and brain imaging.

Suspected HSV encephalitis is a medical emergency requiring prompt intravenous aciclovir, without waiting for confirmatory testing when clinical suspicion is high.

27. HSV Meningitis

HSV can also cause meningitis.

HSV-2 is particularly associated with aseptic meningitis and recurrent lymphocytic meningitis.

Patients may develop headache, fever, photophobia and neck stiffness.

Cerebrospinal fluid typically demonstrates a lymphocytic inflammatory response.

HSV PCR can help establish the diagnosis.

Management depends on disease severity, immune status and the clinical syndrome.

28. Neonatal Herpes

Neonatal herpes is a serious infection acquired most commonly during delivery through exposure to infected genital secretions or lesions.

The risk is particularly high when maternal genital HSV infection is newly acquired near the time of delivery.

Neonatal infection may present as skin, eye and mouth disease, central nervous system infection or disseminated infection.

Disseminated neonatal HSV may involve the liver, lungs and other organs.

Neonatal herpes requires urgent investigation and intravenous aciclovir because delayed treatment can result in severe neurological injury or death.

29. HSV Infection in Immunocompromised Patients

HSV infection may be more severe in patients with impaired immune function.

Individuals with advanced HIV infection, organ transplantation or significant immunosuppression may develop extensive or persistent lesions.

Ulcers may be unusually large, deep or slow to heal.

Disseminated infection or visceral involvement can occasionally occur.

These patients may require prolonged antiviral therapy and assessment for antiviral resistance when lesions fail to respond.

Diagnosis of Herpes Simplex Virus Infection

30. Clinical Diagnosis

Genital herpes may be suspected from the characteristic appearance of grouped vesicles and painful superficial ulcers.

A history of recurrent lesions at similar anatomical sites supports the diagnosis.

However, clinical examination alone is not sufficiently reliable because other infections and inflammatory conditions can produce similar lesions.

Some patients have atypical manifestations without obvious vesicles.

Therefore, laboratory confirmation is recommended when appropriate.

31. HSV Polymerase Chain Reaction (PCR)

HSV nucleic acid amplification testing, commonly performed by PCR, is the preferred laboratory test for active genital lesions.

A swab is collected from a fresh vesicle or ulcer.

PCR detects HSV genetic material and can distinguish HSV-1 from HSV-2.

This distinction is useful because the two types differ in their expected recurrence patterns.

PCR is generally more sensitive than viral culture.

However, a negative result does not completely exclude HSV infection, particularly when lesions are healing or viral shedding is intermittent.

32. Viral Culture

HSV can be isolated from clinical lesions using viral culture.

However, culture is less sensitive than PCR, especially when lesions are older or beginning to heal.

Its sensitivity also decreases during recurrent episodes.

For this reason, PCR-based testing is generally preferred when available.

Viral culture may still be useful in selected circumstances, including specialised investigations.

33. HSV Serological Testing

Type-specific HSV serology detects antibodies against HSV-1 or HSV-2.

It may be useful in selected situations, such as recurrent symptoms with negative lesion testing or assessment of a partner’s infection status.

However, HSV antibodies may take weeks to develop after acquisition.

HSV-1 seropositivity does not establish whether infection is oral or genital.

Low-positive HSV-2 antibody results may also require confirmatory testing because false-positive reactions occur.

HSV IgM testing is not recommended for routine diagnosis because it is unreliable and cannot reliably distinguish new from recurrent infection.

Treatment of Herpes Simplex Virus

34. Principles of Treatment

The treatment of genital herpes aims to reduce the duration and severity of symptoms, accelerate lesion healing and decrease the frequency of recurrences.

Antiviral therapy can also reduce viral shedding and, in selected circumstances, the risk of transmission.

However, currently available antiviral drugs do not eradicate latent HSV from sensory ganglia.

Therefore, treatment controls viral replication rather than permanently curing the infection.

The main antiviral medications used are aciclovir, valaciclovir and famciclovir.

35. Aciclovir

Aciclovir is a nucleoside analogue with activity against HSV-1 and HSV-2.

It is activated initially by viral thymidine kinase within infected cells.

Subsequent phosphorylation by host enzymes produces aciclovir triphosphate, the active form.

This compound inhibits viral DNA polymerase and interferes with viral DNA synthesis.

As a result, viral replication is suppressed.

Aciclovir is particularly useful because its activation preferentially occurs in infected cells, providing selective antiviral activity.

36. Effect of Aciclovir on Genital Herpes

The original notes state that aciclovir reduces the time during which lesions are present.

This is correct.

Aciclovir can shorten the duration of symptoms, reduce viral shedding and accelerate lesion healing.

It is most effective when started early during an outbreak.

For recurrent herpes, treatment ideally begins during the prodromal period or within approximately one day of lesion onset.

Aciclovir does not remove the latent virus from sensory ganglia and therefore cannot prevent every future recurrence.

37. Treatment of the First Clinical Episode

A first clinical episode of genital herpes is generally treated with oral antiviral therapy.

One commonly recommended adult regimen is aciclovir 400 mg orally three times daily for 7–10 days.

Alternative regimens include valaciclovir or famciclovir.

Treatment may be extended when lesions have not healed adequately.

Supportive care includes analgesia, hydration and measures to reduce local discomfort.

Patients with severe complications, such as disseminated infection or significant neurological involvement, may require hospitalisation and intravenous aciclovir.

38. Episodic Treatment of Recurrent Herpes

Episodic antiviral therapy is used to treat individual recurrent outbreaks.

Patients begin treatment when prodromal symptoms or early lesions appear.

Short courses of aciclovir, valaciclovir or famciclovir may be prescribed.

Early initiation can reduce the duration and severity of the episode.

This approach is particularly suitable for patients who experience infrequent recurrences.

39. Suppressive Antiviral Therapy

Suppressive therapy involves taking antiviral medication regularly to reduce the frequency of recurrent outbreaks.

It may be considered for patients with frequent or distressing recurrences.

Common options include daily aciclovir or valaciclovir.

Suppressive treatment can substantially reduce recurrent genital herpes episodes.

In patients with genital HSV-2 infection, daily valaciclovir has also been shown to reduce transmission risk in certain discordant heterosexual couples.

However, transmission remains possible because antiviral treatment does not completely eliminate viral shedding.

40. Valaciclovir

Valaciclovir is a prodrug of aciclovir.

After oral administration, it is converted into aciclovir within the body.

It has improved oral bioavailability compared with aciclovir.

This allows less frequent dosing in many treatment regimens.

Valaciclovir is used for first episodes, recurrent outbreaks and suppressive treatment of genital herpes.

41. Famciclovir

Famciclovir is an oral prodrug that is converted into penciclovir.

Penciclovir inhibits viral DNA polymerase after activation within infected cells.

Famciclovir is an alternative treatment for genital HSV infection.

It can be used for episodic or suppressive therapy.

The choice between aciclovir, valaciclovir and famciclovir depends on clinical circumstances, dosing convenience, availability and patient preference.

42. Adverse Effects and Precautions

Aciclovir and related antiviral medications are generally well tolerated.

Possible adverse effects include nausea, headache and gastrointestinal discomfort.

Aciclovir is eliminated primarily through the kidneys, so dosage adjustment may be necessary in patients with impaired renal function.

Intravenous aciclovir can occasionally cause crystal-associated kidney injury, particularly when hydration is inadequate or infusion is too rapid.

Rare neurological adverse effects may occur, especially when drug accumulation develops in renal impairment.

Appropriate dosing and renal monitoring are important in susceptible patients.

Prevention of Genital Herpes

43. Reducing Sexual Transmission

HSV transmission can be reduced through several preventive measures.

Avoiding sexual contact during active genital lesions or prodromal symptoms is particularly important because viral shedding is often increased.

Condoms reduce the risk of transmission but do not provide complete protection because infected skin may remain uncovered.

Daily suppressive antiviral therapy may reduce transmission risk in selected patients with genital HSV-2 infection.

Patients should understand that asymptomatic shedding can still occur.

44. Partner Counselling

Patients diagnosed with genital herpes should receive clear information about the lifelong nature of HSV infection.

A diagnosis does not establish when the infection was acquired because HSV may remain asymptomatic for prolonged periods.

Partners may already have HSV infection without recognised symptoms.

Type-specific testing may be considered in selected situations after appropriate counselling.

Open communication and an understanding of asymptomatic transmission are important aspects of management.

45. Genital Herpes During Pregnancy

Genital HSV infection during pregnancy is clinically important because of the risk of neonatal herpes.

The greatest risk of neonatal transmission occurs when a pregnant patient acquires genital HSV near the time of delivery.

Patients with recurrent genital herpes generally have a lower transmission risk because pre-existing maternal antibodies provide some protection.

Suppressive antiviral therapy may be offered near the end of pregnancy to reduce genital recurrences at delivery.

Caesarean delivery is generally recommended when active genital lesions or prodromal symptoms are present at the onset of labour.

Management should follow obstetric guidelines and consider the timing and type of maternal infection.

HSV and Other Causes of Genital Ulceration

46. Herpes Simplex Virus

Genital herpes typically produces multiple painful vesicles that rupture into shallow ulcers.

Patients may experience burning, tingling, dysuria and tender inguinal lymphadenopathy.

Recurrent episodes are common, particularly with genital HSV-2.

HSV PCR from a lesion is the preferred diagnostic test.

Treatment involves antiviral medication such as aciclovir.

47. Primary Syphilis

Primary syphilis is caused by Treponema pallidum.

It classically produces a solitary, painless, indurated genital ulcer called a chancre.

Regional lymphadenopathy is usually non-tender.

Diagnosis relies on serological testing and direct detection methods where available.

Treatment is penicillin G.

48. Chancroid

Chancroid is caused by Haemophilus ducreyi.

It classically produces painful genital ulcers with soft, irregular edges.

Tender inguinal lymphadenopathy may occur, sometimes progressing to suppurative buboes.

Chancroid is less common than genital herpes in many regions.

The diagnosis and treatment differ from those of HSV infection.

49. Important Examination Distinction

The classical clinical distinction between genital herpes and primary syphilis is based on ulcer characteristics.

Genital herpes → Multiple painful vesicles and shallow ulcers.

Primary syphilis → Usually a painless, indurated chancre.

Chancroid → Painful, soft genital ulcer with tender lymphadenopathy.

However, these findings are not absolute, and laboratory testing is important because clinical presentations may overlap.

Important Corrections and Clarifications

50. HSV-1 and HSV-2 Distribution

The original notes state that HSV-1 mainly affects the oral region and HSV-2 mainly affects the genital region.

This remains a useful traditional association.

However, HSV-1 is also an important cause of genital herpes, and HSV-2 can occasionally cause oral infection.

Therefore, viral type does not exclusively determine anatomical location.

51. Lifelong Dormancy

The original notes correctly state that HSV can remain dormant for very long periods.

HSV establishes lifelong latency within sensory nerve ganglia.

Reactivation may occur after months or years, even in patients who have remained asymptomatic for prolonged periods.

52. Painful Genital Ulceration

The original notes correctly identify painful genital ulceration as a major feature of HSV infection.

The classical lesion begins as a vesicle that ruptures to form a shallow, painful ulcer.

However, many HSV infections are asymptomatic or produce atypical symptoms.

Therefore, the absence of painful ulcers does not exclude HSV infection.

53. Role of Aciclovir

Aciclovir inhibits viral DNA synthesis and reduces the duration and severity of symptomatic outbreaks.

It can also be used as daily suppressive therapy.

However, it does not eliminate latent HSV from sensory ganglia.

Therefore, HSV infection may recur despite previous successful treatment.

54. Severity of Recurrent Infection

The original notes state that recurrent episodes are normally less aggressive than the initial infection.

This is generally correct.

Recurrent episodes usually involve fewer lesions, milder symptoms and shorter healing times.

Systemic symptoms are also less common.

However, recurrence severity varies, and immunocompromised individuals may experience severe or persistent disease.

Important Clinical Associations – Note Form

55. HSV-1

HSV-1 is predominantly associated with oral herpes, herpes labialis and primary gingivostomatitis.

It is also an important cause of genital herpes, herpetic keratitis and herpes simplex encephalitis.

Following oral infection, latency classically occurs in the trigeminal ganglion.

56. HSV-2

HSV-2 is predominantly associated with genital herpes.

It commonly establishes latency within sacral sensory ganglia.

Genital HSV-2 infection generally produces more frequent recurrences and asymptomatic genital shedding than genital HSV-1 infection.

HSV-2 is also associated with aseptic meningitis.

57. Primary Genital Herpes

Primary genital herpes may cause multiple painful vesicles and ulcers accompanied by fever, malaise, dysuria and tender inguinal lymphadenopathy.

The first clinical episode may be more severe and prolonged than later recurrences.

Oral antiviral therapy is recommended for symptomatic first episodes.

58. Recurrent Genital Herpes

Recurrent genital herpes results from reactivation of latent HSV.

Patients may experience tingling, itching or burning before lesions develop.

Recurrent outbreaks are generally shorter and less severe than the initial symptomatic episode.

59. Aciclovir

Aciclovir is a nucleoside analogue activated initially by viral thymidine kinase.

Its active metabolite inhibits viral DNA polymerase.

It reduces viral replication, accelerates lesion healing and decreases symptom duration.

It does not eradicate latent HSV.

60. HSV Encephalitis

HSV-1 encephalitis classically affects the temporal lobes.

Patients may develop fever, altered mental status, seizures and focal neurological abnormalities.

Prompt intravenous aciclovir is essential.

61. HSV Keratitis

HSV keratitis may produce dendritic corneal ulcers.

Patients may develop eye pain, photophobia and blurred vision.

Recurrent disease can cause corneal scarring and visual impairment.

62. Neonatal HSV

Neonatal HSV may cause skin, eye and mouth disease, encephalitis or disseminated infection.

Transmission commonly occurs during delivery.

Neonatal HSV is a serious infection requiring urgent intravenous aciclovir.

Key Clinical Pattern

The defining characteristic of herpes simplex virus is its ability to cause recurrent painful mucocutaneous lesions through reactivation of lifelong latent infection within sensory nerve ganglia.

HSV-1 → Mainly oral herpes, but can also cause genital herpes.

HSV-2 → Mainly genital herpes, with more frequent genital recurrences.

Primary genital herpes → Multiple painful vesicles and shallow ulcers, sometimes with fever and tender lymphadenopathy.

Viral latency → HSV persists within sensory nerve ganglia for life.

Trigeminal ganglion → Classical site of latency following oral HSV infection.

Sacral ganglia → Classical site of latency following genital HSV infection.

Reactivation → Virus travels along sensory nerves and may produce recurrent lesions.

Recurrent herpes → Usually milder, shorter and less extensive than the initial symptomatic episode.

Asymptomatic viral shedding → HSV transmission can occur without visible lesions.

HSV PCR → Preferred diagnostic test for active genital lesions.

Aciclovir → Inhibits viral DNA polymerase and reduces lesion duration.

Suppressive antiviral therapy → Reduces recurrence frequency and viral shedding.

HSV-1 encephalitis → Temporal lobe involvement requiring urgent intravenous aciclovir.

HSV keratitis → Dendritic corneal ulceration.

Neonatal herpes → Potentially severe infection acquired around delivery.

For examinations, remember the classical association: HSV causes painful genital vesicles and ulcers, remains latent within sensory ganglia, and can reactivate repeatedly. Aciclovir shortens outbreaks and suppresses viral replication but does not provide a permanent cure.