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Infectious Diseases and Microbiology: Gonorrhea
Basics
Description
Gonorrhea is caused by Neisseria gonorrhoeae, a gram-negative intracellular diplococcus that infects humans only. Spread occurs through direct mucosal inoculation during sexual contact or childbirth. Transmission is more efficient from men to women, and a single sexual exposure can infect up to half of female partners.
Epidemiology
Gonorrhea remains a major global public health issue and contributes substantially to morbidity, especially in developing regions. Worldwide incidence has been estimated at roughly 62 million new infections annually, with highest rates in sub-Saharan Africa, South and Southeast Asia, the Caribbean, and Latin America. In the United States, hundreds of thousands of cases were reported in 2008 with the highest rates in females aged 15–19 and males aged 20–24; reported rates were higher in African American and Hispanic populations than in White populations.
Risk Factors
Risk is increased by female sex, age under 25, prior gonorrhea or other STIs, new or multiple partners, inconsistent condom use, commercial sex work, drug use, and travel to high-prevalence countries.
General Prevention
Control relies on early detection, immediate treatment at diagnosis, and treatment of sexual partners. Partners within 60 days before symptom onset should be evaluated and treated. Delaying sexual debut, reducing partner number, and consistent condom use decrease transmission.
Etiology
Disease is due to N. gonorrhoeae, a nonmotile, non–spore-forming gram-negative diplococcus.
Commonly Associated Conditions
Coinfection with other STIs is common; Chlamydia coinfection occurs in about one-third of cases. Gonorrhea also increases susceptibility to acquiring HIV.
Diagnosis
Clinical manifestations depend on infection site, bacterial strain, host factors, sex, and coinfections. Many infections are asymptomatic in both sexes. Incubation is typically 2–7 days. In men, urethritis usually begins with dysuria followed by purulent discharge, and acute epididymitis is the most frequent complication. In women, urethritis can cause dysuria, frequency, and urgency, and cervicitis may develop with purulent discharge, cramping, dyspareunia, and postcoital or intermenstrual bleeding; symptoms often intensify around menstruation. Untreated infection can ascend, causing pelvic inflammatory disease with infertility and chronic pelvic pain. Conjunctivitis usually results from autoinoculation and can rapidly threaten vision. In neonates, infection is commonly ophthalmia neonatorum acquired during delivery; ocular prophylaxis with agents such as silver nitrate drops or tetracycline ointment is used for prevention. Disseminated gonococcal infection may present with fever, rash, tenosynovitis, and septic arthritis and can resemble an influenza-like illness without obvious mucosal symptoms, so urethral/cervical, rectal, and pharyngeal sites should be sampled.
Diagnostic Tests and Interpretation
Laboratory Studies
In symptomatic men, Gram stain of urethral discharge can show polymorphonuclear cells and gram-negative intracellular diplococci, but Gram stain performs poorly with endocervical, rectal, and pharyngeal specimens. Culture allows antimicrobial susceptibility testing and should be performed on selective media such as modified Thayer–Martin (or equivalent) with aerobic conditions and increased CO₂; rapid processing is essential because gonococci do not tolerate drying. Strains linked to dissemination may be more fastidious and harder to grow. Nucleic acid–based tests can detect N. gonorrhoeae from swabs or urine with sensitivity and specificity comparable or better than culture, but cost is higher and cross-reactivity with nonpathogenic Neisseria species can occur.
Differential Diagnosis
Urethritis can be nongonococcal due to Chlamydia, Ureaplasma, Mycoplasma genitalium, Haemophilus vaginalis, HSV, adenovirus, and others. Vaginal symptoms may reflect candidiasis, bacterial vaginosis, trichomoniasis, or noninfectious etiologies such as chemical irritation, allergy, fistula, or pregnancy-related leukorrhea. Disseminated gonococcal infection must be distinguished from meningococcemia, ecthyma gangrenosum, other bacteremias, septic arthritis from other bacteria, and reactive arthritis.
Treatment
Medications
CDC-recommended therapy has centered on cephalosporins. For uncomplicated urethral, cervical, or rectal infection, recommended single-dose options include ceftriaxone 125 mg IM, cefixime 400 mg PO, or spectinomycin 2 g IM. Pharyngeal infection is harder to eradicate and is treated with ceftriaxone 125 mg IM as the preferred regimen. Gonococcal conjunctivitis is treated with ceftriaxone 125 mg IM once, with saline eye irrigation as an optional adjunct. Disseminated infection is treated with parenteral cephalosporin-based regimens such as ceftriaxone 1 g IM/IV daily or cefotaxime/ceftizoxime 1 g IV three times daily, or spectinomycin 2 g IM twice daily; continue parenteral therapy for 24–48 hours after clinical improvement, then transition to an oral agent such as cefixime 400 mg PO twice daily to complete a total of one week. If chlamydial infection has not been excluded, provide concurrent chlamydia therapy. Fluoroquinolones are not recommended as first-line therapy in the United States because of widespread resistance.
Additional Treatment
Because Chlamydia coinfection is common, initial management should cover chlamydia (e.g., azithromycin or doxycycline) unless it has been ruled out.
Ongoing Care and Follow-Up
Patient Monitoring
A routine test-of-cure is not required after treating uncomplicated infection. If symptoms persist, obtain culture with susceptibility testing; the most common reason for apparent treatment failure is reinfection from an untreated partner.
Patient Education
Advise consistent condom use and provide instruction on correct condom use.
Complications
The most important complication is pelvic inflammatory disease from ascending infection, which can lead to tubo-ovarian abscess, pelvic peritonitis, and Fitz-Hugh–Curtis syndrome, with long-term infertility and chronic pelvic pain. In men, complications include epididymitis, periurethritis, balanitis, acute or chronic prostatitis, orchitis, seminal vasculitis, and infection of Tyson and Cowper glands. Disseminated gonococcemia is more common in women, with menstruation increasing risk, and typically causes tenosynovitis, migratory arthritis, and peripheral skin lesions that may be maculopapular or pustular; blood cultures are positive in only a minority of cases. Endocarditis and meningitis are rare in the antibiotic era.
Basics
Description
Gonorrhea is caused by Neisseria gonorrhoeae, a gram-negative intracellular diplococcus that infects humans only. Spread occurs through direct mucosal inoculation during sexual contact or childbirth. Transmission is more efficient from men to women, and a single sexual exposure can infect up to half of female partners.
Epidemiology
Gonorrhea remains a major global public health issue and contributes substantially to morbidity, especially in developing regions. Worldwide incidence has been estimated at roughly 62 million new infections annually, with highest rates in sub-Saharan Africa, South and Southeast Asia, the Caribbean, and Latin America. In the United States, hundreds of thousands of cases were reported in 2008 with the highest rates in females aged 15–19 and males aged 20–24; reported rates were higher in African American and Hispanic populations than in White populations.
Risk Factors
Risk is increased by female sex, age under 25, prior gonorrhea or other STIs, new or multiple partners, inconsistent condom use, commercial sex work, drug use, and travel to high-prevalence countries.
General Prevention
Control relies on early detection, immediate treatment at diagnosis, and treatment of sexual partners. Partners within 60 days before symptom onset should be evaluated and treated. Delaying sexual debut, reducing partner number, and consistent condom use decrease transmission.
Etiology
Disease is due to N. gonorrhoeae, a nonmotile, non–spore-forming gram-negative diplococcus.
Commonly Associated Conditions
Coinfection with other STIs is common; Chlamydia coinfection occurs in about one-third of cases. Gonorrhea also increases susceptibility to acquiring HIV.
Diagnosis
Clinical manifestations depend on infection site, bacterial strain, host factors, sex, and coinfections. Many infections are asymptomatic in both sexes. Incubation is typically 2–7 days. In men, urethritis usually begins with dysuria followed by purulent discharge, and acute epididymitis is the most frequent complication. In women, urethritis can cause dysuria, frequency, and urgency, and cervicitis may develop with purulent discharge, cramping, dyspareunia, and postcoital or intermenstrual bleeding; symptoms often intensify around menstruation. Untreated infection can ascend, causing pelvic inflammatory disease with infertility and chronic pelvic pain. Conjunctivitis usually results from autoinoculation and can rapidly threaten vision. In neonates, infection is commonly ophthalmia neonatorum acquired during delivery; ocular prophylaxis with agents such as silver nitrate drops or tetracycline ointment is used for prevention. Disseminated gonococcal infection may present with fever, rash, tenosynovitis, and septic arthritis and can resemble an influenza-like illness without obvious mucosal symptoms, so urethral/cervical, rectal, and pharyngeal sites should be sampled.
Diagnostic Tests and Interpretation
Laboratory Studies
In symptomatic men, Gram stain of urethral discharge can show polymorphonuclear cells and gram-negative intracellular diplococci, but Gram stain performs poorly with endocervical, rectal, and pharyngeal specimens. Culture allows antimicrobial susceptibility testing and should be performed on selective media such as modified Thayer–Martin (or equivalent) with aerobic conditions and increased CO₂; rapid processing is essential because gonococci do not tolerate drying. Strains linked to dissemination may be more fastidious and harder to grow. Nucleic acid–based tests can detect N. gonorrhoeae from swabs or urine with sensitivity and specificity comparable or better than culture, but cost is higher and cross-reactivity with nonpathogenic Neisseria species can occur.
Differential Diagnosis
Urethritis can be nongonococcal due to Chlamydia, Ureaplasma, Mycoplasma genitalium, Haemophilus vaginalis, HSV, adenovirus, and others. Vaginal symptoms may reflect candidiasis, bacterial vaginosis, trichomoniasis, or noninfectious etiologies such as chemical irritation, allergy, fistula, or pregnancy-related leukorrhea. Disseminated gonococcal infection must be distinguished from meningococcemia, ecthyma gangrenosum, other bacteremias, septic arthritis from other bacteria, and reactive arthritis.
Treatment
Medications
CDC-recommended therapy has centered on cephalosporins. For uncomplicated urethral, cervical, or rectal infection, recommended single-dose options include ceftriaxone 125 mg IM, cefixime 400 mg PO, or spectinomycin 2 g IM. Pharyngeal infection is harder to eradicate and is treated with ceftriaxone 125 mg IM as the preferred regimen. Gonococcal conjunctivitis is treated with ceftriaxone 125 mg IM once, with saline eye irrigation as an optional adjunct. Disseminated infection is treated with parenteral cephalosporin-based regimens such as ceftriaxone 1 g IM/IV daily or cefotaxime/ceftizoxime 1 g IV three times daily, or spectinomycin 2 g IM twice daily; continue parenteral therapy for 24–48 hours after clinical improvement, then transition to an oral agent such as cefixime 400 mg PO twice daily to complete a total of one week. If chlamydial infection has not been excluded, provide concurrent chlamydia therapy. Fluoroquinolones are not recommended as first-line therapy in the United States because of widespread resistance.
Additional Treatment
Because Chlamydia coinfection is common, initial management should cover chlamydia (e.g., azithromycin or doxycycline) unless it has been ruled out.
Ongoing Care and Follow-Up
Patient Monitoring
A routine test-of-cure is not required after treating uncomplicated infection. If symptoms persist, obtain culture with susceptibility testing; the most common reason for apparent treatment failure is reinfection from an untreated partner.
Patient Education
Advise consistent condom use and provide instruction on correct condom use.
Complications
The most important complication is pelvic inflammatory disease from ascending infection, which can lead to tubo-ovarian abscess, pelvic peritonitis, and Fitz-Hugh–Curtis syndrome, with long-term infertility and chronic pelvic pain. In men, complications include epididymitis, periurethritis, balanitis, acute or chronic prostatitis, orchitis, seminal vasculitis, and infection of Tyson and Cowper glands. Disseminated gonococcemia is more common in women, with menstruation increasing risk, and typically causes tenosynovitis, migratory arthritis, and peripheral skin lesions that may be maculopapular or pustular; blood cultures are positive in only a minority of cases. Endocarditis and meningitis are rare in the antibiotic era.
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