Infectious Disease and Microbiology – Ewingella americana

Overview

Ewingella americana is a rare aerobic Gram-negative bacillus historically classified within the Enterobacteriaceae. It is infrequently recovered from clinical specimens, and because of its rarity, its overall clinical significance and pathogenic potential remain incompletely defined.

Reported infections have occurred particularly in immunocompromised patients and include bacteremia, wound infections, and occasional respiratory tract infections.

Microbiologic Characteristics

Ewingella americana is:

• An aerobic Gram-negative bacillus

• Historically classified within the Enterobacteriaceae group

• A rare opportunistic human pathogen

Its uncommon isolation makes it difficult to establish its precise role in many clinical settings.

Epidemiology

E. americana is rarely recovered in clinical cultures.

Consequently, considerably less is known about its epidemiology than about more common Gram-negative pathogens.

Clinical Significance

The clinical significance of E. americana can sometimes be uncertain, particularly when it is recovered from specimens that may contain colonizing organisms.

However, documented invasive infections indicate that it can function as an opportunistic pathogen, especially in susceptible hosts.

Risk Factors

Reported infections are particularly relevant in patients with:

• Immunocompromising conditions

• Significant underlying disease

• Wounds or disrupted tissue barriers

• Healthcare exposure

Because relatively few cases have been reported, the complete spectrum of risk factors remains uncertain.

Bacteremia

E. americana has been reported as a cause of bacteremia, particularly in immunocompromised patients.

Isolation from blood should therefore be evaluated carefully in conjunction with the patient’s clinical condition rather than automatically dismissed because the organism is uncommon.

Wound Infection

The organism has also been associated with wound infections, particularly in patients with impaired host defenses.

Clinical significance is more convincing when the organism is recovered from an infected wound together with compatible inflammatory findings.

Respiratory Tract Infection

E. americana has rarely been associated with respiratory tract infection.

Because respiratory specimens can contain colonizing organisms, recovery from the respiratory tract should be interpreted together with clinical and radiologic evidence of infection.

Diagnosis

Diagnosis is established by:

Culture of the organism

Because E. americana is unusual, accurate laboratory identification is important.

For clinically significant isolates, antimicrobial susceptibility testing is particularly valuable because predictable susceptibility patterns cannot always be assumed.

Treatment

There are limited clinical data regarding optimal antimicrobial therapy for E. americana infection.

The source reports activity with agents including:

• Cefotaxime

• Piperacillin–tazobactam

• Trimethoprim–sulfamethoxazole

However, antimicrobial susceptibility should ideally be determined for the individual isolate.

Multidrug Resistance

An important concern is that multidrug-resistant isolates have been reported.

Therefore:

Rare organism + uncertain susceptibility + possible multidrug resistance

→ Culture and susceptibility-guided therapy are particularly important

Combination Therapy

The source describes clinical use of combinations involving:

Trimethoprim–sulfamethoxazole

or

Cefotaxime

or

An antipseudomonal penicillin

combined with an:

Aminoglycoside

Because evidence is limited, these historical treatment approaches should not be considered universally appropriate for every isolate.

Treatment Principle

The most important therapeutic concept is:

Identify the organism

• ●

Perform antimicrobial susceptibility testing

• ●

Choose therapy according to susceptibility and infection severity

This is especially important because E. americana is uncommon and antimicrobial resistance has been reported.

High-Yield Clinical Pattern

Immunocompromised patient

• ●

Bacteremia or wound infection

• ●

Unusual aerobic Gram-negative bacillus

• ●

Potential multidrug resistance

→ Consider Ewingella americana

Exam Essentials

Organism: Ewingella americana

Type: Gram-negative bacillus

Oxygen requirement: Aerobic

Traditional classification: Enterobacteriaceae

Frequency: Very rare

Clinical significance: Incompletely defined

Important host: Immunocompromised patient

Major reported infections: Bacteremia and wound infection

Respiratory infection: Rare

Diagnosis: Culture

Important laboratory step: Antimicrobial susceptibility testing

Resistance: Multidrug resistance has been reported

Reported active agents in source: Cefotaxime, piperacillin–tazobactam, trimethoprim–sulfamethoxazole

Treatment principle: Susceptibility-guided therapy

Key clinical pearl: Ewingella americana is a rare opportunistic Gram-negative bacillus associated mainly with bacteremia and wound infection in immunocompromised patients; because clinical experience is limited and multidrug resistance can occur, antimicrobial susceptibility testing is central to treatment selection.

Infectious Disease and Microbiology – Eubacterium Species

Overview

Eubacterium species are anaerobic, pleomorphic Gram-positive bacilli that form part of the normal human microbiota. Because these organisms normally colonize the body, their recovery from a clinical specimen does not automatically establish that they are causing infection.

When pathogenic, Eubacterium species are commonly associated with polymicrobial infections, particularly abscesses, periodontal disease, and infections arising from sites containing anaerobic flora.

Important Species

Species described in this group include:

• Eubacterium lentum

• Eubacterium nodatum

• Eubacterium timidum

• Other Eubacterium species

Some organisms historically classified as Eubacterium have undergone taxonomic reclassification, so older names may still appear in infectious-disease literature.

Microbiologic Characteristics

Eubacterium species are:

• Anaerobic

• Gram-positive bacilli

• Pleomorphic in appearance

• Components of normal human flora

Their anaerobic nature means that specimens must be collected and transported appropriately if culture is required.

Epidemiology

Eubacterium species are members of the normal human microbiota.

They may inhabit sites such as the gastrointestinal tract and oral cavity.

Because colonization is common, isolation of an organism must always be interpreted in the context of the patient’s clinical syndrome and the specimen source.

Colonization vs. Infection

A particularly important principle is:

Positive culture ≠ necessarily active infection

Isolation from a normally colonized site may simply represent normal flora or contamination.

Evidence for true infection is stronger when the organism is recovered from a normally sterile site, particularly when accompanied by compatible clinical findings.

Clinical Infections

When Eubacterium species cause disease, infections may include:

• Abscesses

• Periodontal infections

• Septic arthritis

• Gynecologic infections such as endometritis

• Other anaerobic infections

These infections are almost always polymicrobial, meaning other bacterial species are frequently present.

Abscesses and Mixed Infections

Eubacterium species may be recovered from abscesses and infections at various anatomical sites.

A typical pattern is:

Disruption of mucosal barrier

→

Normal anaerobic flora enters deeper tissue

→

Polymicrobial abscess or invasive infection

This is characteristic of many infections caused by endogenous anaerobic flora.

Periodontal Disease

Certain Eubacterium species have been associated with periodontal disease.

The oral cavity contains a complex anaerobic microbiome, so periodontal infections are usually polymicrobial rather than caused by a single organism.

Eubacterium lentum

The source associates Eubacterium lentum with:

Septic arthritis in patients with colonic lesions

This association suggests that disruption of the gastrointestinal mucosal barrier may permit organisms from intestinal flora to enter the bloodstream and subsequently involve a joint.

Eubacterium nodatum

The source associates Eubacterium nodatum with:

Endometritis in women using an intrauterine device (IUD)

This represents another example of an anaerobic organism associated with infection following alteration or disruption of normal mucosal environments.

Diagnosis

Diagnosis is established by:

Culture using appropriate anaerobic media

Successful isolation requires appropriate specimen collection and maintenance of anaerobic conditions during transport and processing.

Interpretation of Culture

Because Eubacterium species are normal flora, laboratory isolation should be interpreted together with:

• Clinical manifestations

• Anatomical source of the specimen

• Presence of abscess or tissue inflammation

• Recovery from a normally sterile site

• Presence of additional organisms

The organism’s presence alone does not prove causation.

Treatment

The source lists:

Penicillin G

or

A cephamycin

as treatment options.

It also lists:

Metronidazole

for anaerobic coverage.

Additional Treatment

Other antimicrobial agents described in the source include:

• Imipenem

• Meropenem

• Clindamycin

• Ureidopenicillins

For clinically significant infection, antimicrobial selection should take into account the susceptibility pattern and other organisms present in a polymicrobial infection.

Source Control

Because these organisms frequently occur in abscesses and mixed anaerobic infections, antimicrobial therapy may need to be combined with appropriate source control.

This can include drainage of an abscess, debridement of infected tissue, or management of an underlying anatomical source.

High-Yield Clinical Pattern

Anaerobic Gram-positive bacillus

• ●

Normally part of human flora

• ●

Recovered from an abscess or other polymicrobial infection

→ Think Eubacterium species

Important Interpretation Pattern

Eubacterium isolated from a colonized site

→ May represent normal flora

Eubacterium isolated from a sterile site + compatible infection

→ More supportive of true invasive infection

Exam Essentials

Genus: Eubacterium

Type: Pleomorphic Gram-positive bacillus

Oxygen requirement: Anaerobic

Normal habitat: Part of normal human flora

Major infection pattern: Polymicrobial anaerobic infection

Common manifestations: Abscesses and periodontal disease

E. lentum: Associated in the source with septic arthritis in patients with colonic lesions

E. nodatum: Associated in the source with endometritis in women using an IUD

Diagnosis: Anaerobic culture

Important diagnostic issue: Isolation does not necessarily indicate infection

Treatment in source: Penicillin G, cephamycins, or metronidazole

Additional agents: Carbapenems, clindamycin, or ureidopenicillins

Management principle: Consider source control for abscesses

Key clinical pearl: Because Eubacterium species are part of the normal human flora, a positive culture does not by itself establish disease; true infections are typically anaerobic, polymicrobial infections, especially abscesses and infections arising after disruption of normal mucosal barriers.

Infectious Disease and Microbiology – Erysipelothrix rhusiopathiae

Overview

Erysipelothrix rhusiopathiae is a Gram-positive bacillus that causes a characteristic occupational skin infection known as erysipeloid. Human infection is uncommon but occurs worldwide and is strongly associated with exposure to fish, shellfish, animals, animal products, or contaminated soil.

Although most infections remain localized to the skin, the organism can occasionally cause diffuse cutaneous disease, bacteremia, and infective endocarditis.

Microbiologic Characteristics

Erysipelothrix rhusiopathiae is an:

• Aerobic Gram-positive bacillus

• Zoonotic pathogen

• Environmental and animal-associated organism

It is especially notable for causing infection after inoculation through minor skin trauma during occupational exposure.

Incubation Period

The incubation period is:

Not clearly defined

Clinical infection usually follows direct inoculation of the organism into damaged skin.

Epidemiology

Human infection is rare but occurs worldwide.

Exposure is classically associated with people who handle:

• Fish

• Crustaceans and shellfish

• Meat or animal carcasses

• Livestock

• Animal products

• Soil contaminated by animals

Occupational risk is therefore increased in fish handlers, butchers, veterinarians, farmers, and similar workers.

Erysipeloid

The classic localized infection caused by E. rhusiopathiae is called:

Erysipeloid

This is a localized cutaneous infection that usually develops at the site of inoculation.

Clinical Features of Erysipeloid

Typical findings include:

• Painful or burning skin lesion

• Erythematous to violaceous discoloration

• Well-demarcated margins

• Gradual peripheral expansion

• Common involvement of the hands or fingers

Systemic symptoms are usually absent or mild in localized disease.

Diffuse Cutaneous Disease

Some patients may develop a more widespread cutaneous eruption accompanied by systemic symptoms.

Possible manifestations include:

• Fever

• Myalgias

• Arthralgias

• Multiple skin lesions

This represents a more extensive form of infection than classic localized erysipeloid.

Bacteremia

Rarely, E. rhusiopathiae can invade the bloodstream and cause:

Bacteremia

Bloodstream infection should raise concern for deeper or systemic involvement.

Infective Endocarditis

One of the most important severe manifestations is:

Infective endocarditis

Historically, E. rhusiopathiae bacteremia has had a notable association with endocarditis.

Patients with systemic infection may therefore require evaluation for cardiac involvement when clinically appropriate.

Diagnosis

Diagnosis is established by:

Culture of the organism

Specimens depend on the clinical syndrome and may include tissue or blood.

Because localized lesions can have relatively few organisms, obtaining an appropriate deeper specimen may improve diagnostic yield.

Treatment

The source recommends:

Penicillin G for 10 days

Penicillin has traditionally been considered an effective treatment for susceptible E. rhusiopathiae infection.

Additional Treatment Options

Alternative agents listed in the source include:

• Cephalosporins

• Clindamycin

• Ciprofloxacin

• Carbapenems such as imipenem or meropenem

Choice of therapy should depend on disease severity and susceptibility when available.

Important Antibiotic Pearl

A useful microbiology distinction is that Erysipelothrix rhusiopathiae is characteristically resistant to vancomycin.

This is clinically important because vancomycin is often used empirically for Gram-positive infections, but it is not a reliable treatment for this organism.

Occupational Exposure Pattern

A classic exposure history is:

Fish or animal handler

• ●

Minor cut or puncture wound

• ●

Painful violaceous hand lesion

→ Think Erysipelothrix rhusiopathiae

Differential Diagnosis

Localized erysipeloid may resemble:

• Cellulitis

• Erysipelas

• Contact dermatitis

• Other occupational skin infections

The exposure history is often the major clue.

High-Yield Clinical Pattern

Handling fish, shellfish, meat, or animals

• ●

Localized painful violaceous skin lesion on the hand

• ●

Gram-positive bacillus

→ Think Erysipelothrix rhusiopathiae

Severe Disease Pattern

Systemic symptoms or bacteremia

• ●

Possible cardiac murmur or persistent bloodstream infection

→ Evaluate for infective endocarditis

Exam Essentials

Organism: Erysipelothrix rhusiopathiae

Type: Gram-positive bacillus

Distribution: Worldwide

Frequency: Rare

Classic disease: Erysipeloid

Typical exposure: Fish, crustaceans, animals, meat, or soil

Common site: Hands and fingers after occupational inoculation

Systemic manifestations: Fever, myalgias, arthralgias

Serious complications: Bacteremia and endocarditis

Diagnosis: Culture

Traditional treatment: Penicillin G

Alternative agents: Cephalosporins, clindamycin, ciprofloxacin, carbapenems

Important resistance clue: Vancomycin resistance

Key clinical pearl: Erysipelothrix rhusiopathiae should be suspected in a fish or animal handler with a painful violaceous hand lesion, and severe bacteremic disease is particularly important because of its association with infective endocarditis.

Infectious Disease and Microbiology – Epidermophyton floccosum

Overview

Epidermophyton floccosum is a dermatophyte mold that causes superficial fungal infections of keratinized tissues. It is an important cause of tinea (dermatomycosis) worldwide.

Unlike some other dermatophytes, E. floccosum typically infects skin and nails but not hair, which helps explain why it does not cause tinea capitis.

⸻

Microbiologic Characteristics

Epidermophyton floccosum is a filamentous fungus characterized by:

• Septate hyaline hyphae

• Growth as a mold

• Dermatophyte behavior with affinity for keratinized tissues

It primarily involves the stratum corneum and nails.

⸻

Epidemiology

E. floccosum is a common cause of dermatophyte infection worldwide.

Transmission is generally associated with contact with infected skin, contaminated surfaces, clothing, towels, or other fomites.

⸻

Clinical Infections

E. floccosum causes superficial dermatophyte infections of the skin and nails.

Important manifestations include:

• Tinea cruris

• Tinea corporis

• Tinea pedis

• Inguinal dermatophytosis

• Onychomycosis

A major distinguishing feature is that it generally does not cause tinea capitis.

⸻

Tinea Cruris

Tinea cruris involves the groin and upper medial thighs.

Typical findings may include:

• Pruritic erythematous plaques

• Scaling

• Well-defined advancing borders

• Central clearing

E. floccosum is an important dermatophyte associated with this syndrome.

⸻

Tinea Corporis

Tinea corporis is dermatophyte infection of glabrous skin.

Lesions are often:

• Annular

• Scaly

• Pruritic

• Expanding outward with a more active border

⸻

Tinea Pedis

Tinea pedis affects the feet and may present with:

• Interdigital scaling and fissuring

• Plantar scaling

• Pruritus

• Maceration

E. floccosum is one of the dermatophytes capable of causing this infection.

⸻

Onychomycosis

E. floccosum can also infect the nails and produce onychomycosis.

Affected nails may become:

• Thickened

• Discolored

• Brittle

• Irregular or dystrophic

Nail infection generally requires a longer course of therapy than localized skin disease.

⸻

Why Tinea Capitis Is Absent

A useful distinguishing feature is:

Epidermophyton floccosum infects skin and nails, but not hair

Therefore:

Tinea capitis is not a typical infection caused by this organism.

This helps distinguish Epidermophyton from dermatophytes in the genera Trichophyton and Microsporum.

⸻

Diagnosis

Diagnosis is based on demonstrating the fungus in appropriate clinical specimens.

Specimens may include:

• Skin scrapings

• Nail material

The organism can be identified by:

• Direct microscopic examination

• Fungal culture

⸻

Microscopy

Direct examination of infected keratinized material may reveal:

Septate hyaline fungal hyphae

This supports the diagnosis of dermatophytosis.

⸻

Culture

Growth in fungal culture allows identification of the dermatophyte and can help distinguish E. floccosum from other causes of tinea.

⸻

Treatment – Extensive or Inflammatory Disease

For extensive or inflammatory manifestations, the source recommends:

Itraconazole 200 mg orally daily for 2–4 weeks

Systemic treatment is generally more appropriate when disease is widespread or difficult to manage with topical therapy alone.

⸻

Treatment – Localized Disease

For localized, noninflammatory infection, the source recommends topical:

Ciclopirox olamine, applied approximately every 12 hours.

Localized dermatophyte infections are commonly treated with topical antifungal agents.

⸻

Onychomycosis Treatment

For nail infection, the source recommends:

Itraconazole 200 mg orally daily for 3–6 months

The prolonged duration reflects the slow growth of nails and difficulty eradicating fungi from the nail plate.

⸻

High-Yield Clinical Pattern

Pruritic scaly dermatophyte infection

Skin or nail involvement

No hair infection

→ Think Epidermophyton floccosum

⸻

Dermatophyte Comparison

Epidermophyton

→ Infects skin and nails

→ Does not infect hair

Trichophyton

→ Can infect skin, hair, and nails

Microsporum

→ Typically infects skin and hair, but not nails

This tissue tropism is a useful exam distinction.

⸻

Exam Essentials

Organism: Epidermophyton floccosum

Type: Dermatophyte mold

Hyphae: Septate, hyaline

Distribution: Worldwide

Main infections: Tinea cruris, corporis, pedis, and onychomycosis

Hair involvement: Absent

Tinea capitis: Not typical

Diagnosis: Direct fungal examination + culture

Localized disease: Topical antifungal therapy

Extensive/inflammatory disease: Systemic itraconazole may be used

Onychomycosis: Requires prolonged systemic treatment

⸻

Key clinical pearl: Epidermophyton floccosum infects skin and nails but not hair, so it can cause multiple forms of tinea and onychomycosis, but not tinea capitis.

Infectious Disease and Microbiology – Enterovirus Group

Overview

Enteroviruses are a major group of small, single-stranded RNA viruses within the family Picornaviridae. They have a worldwide distribution and commonly infect humans.

The enterovirus group includes polioviruses, coxsackieviruses, echoviruses, and several numbered enteroviruses. Different members can cause illnesses ranging from mild febrile disease to conjunctivitis, meningitis, encephalitis, myocarditis, hand-foot-and-mouth disease, and poliomyelitis-like neurologic syndromes.

Picornaviridae

Two major groups of Picornaviridae commonly associated with human disease are:

• Enteroviruses

• Rhinoviruses

Both are small RNA viruses, but their tissue tropism and clinical manifestations differ considerably.

Enterovirus Subgroups

Traditionally, the enterovirus group includes:

• Polioviruses – serotypes 1–3

• Coxsackievirus A – multiple serotypes

• Coxsackievirus B – multiple serotypes

• Echoviruses

• Numbered enteroviruses, including EV-A71 and EV-D68

Older classifications sometimes referred to hepatitis A virus as enterovirus 72, but hepatitis A virus is now classified in the genus Hepatovirus within Picornaviridae rather than as an enterovirus.

Microbiologic Characteristics

Enteroviruses are:

• Single-stranded RNA viruses

• Positive-sense RNA viruses

• Nonenveloped (naked)

• Icosahedral

Their lack of an envelope contributes to their ability to remain relatively stable in the environment.

Epidemiology

Enterovirus infections are common worldwide.

Transmission frequently occurs through the fecal–oral route, although some enteroviruses can also spread through respiratory secretions or direct contact with contaminated material.

Incubation Period

The incubation period varies considerably depending on the specific enterovirus and clinical syndrome.

For acute hemorrhagic conjunctivitis, the source describes a particularly short incubation period of:

12–72 hours

This short incubation can contribute to rapid spread during outbreaks.

Clinical Spectrum

Enteroviruses can cause a remarkably broad range of diseases, including:

• Febrile illness

• Skin and mucosal eruptions

• Hand-foot-and-mouth disease

• Herpangina

• Acute hemorrhagic conjunctivitis

• Aseptic meningitis

• Encephalitis

• Myocarditis and pericarditis

• Pleurodynia

• Poliomyelitis and poliomyelitis-like syndromes

• Severe neonatal infection

The clinical syndrome varies according to the specific virus and host.

Acute Hemorrhagic Conjunctivitis

Enterovirus 70 (EV-70) is classically associated with acute hemorrhagic conjunctivitis.

The illness has a rapid onset and can spread efficiently between individuals.

Clinical Features of Acute Hemorrhagic Conjunctivitis

Typical manifestations include:

• Acute eye pain or irritation

• Conjunctival redness

• Eyelid swelling

• Excessive tearing

• Foreign-body sensation

• Subconjunctival hemorrhage

The hemorrhagic appearance is a characteristic feature.

Enterovirus A71

Enterovirus A71 (EV-A71) is an important neurotropic enterovirus.

It can cause:

• Hand-foot-and-mouth disease

• Skin rash

• Meningitis

• Encephalitis

• Brainstem encephalitis

• Acute flaccid paralysis or a poliomyelitis-like syndrome

Young children can develop particularly severe neurologic disease.

Poliomyelitis-Like Syndrome

Some non-polio enteroviruses can affect motor neurons and produce acute flaccid weakness or paralysis resembling poliomyelitis.

Thus:

Acute flaccid paralysis does not automatically mean poliovirus infection.

Other enteroviruses should also be considered.

Meningitis and Encephalitis

Enteroviruses are important causes of aseptic meningitis.

Neurologic manifestations may include:

• Fever

• Headache

• Neck stiffness

• Photophobia

• Vomiting

When brain tissue is involved, patients may develop encephalitis, characterized by altered mental status, seizures, or other neurologic abnormalities.

Diagnosis

Traditional diagnostic methods include:

• Cell culture

• Serologic testing

Serology may provide supportive evidence in selected clinical situations.

Molecular Diagnosis

In modern clinical practice, RT-PCR and other nucleic-acid amplification tests are important methods for detecting enterovirus RNA.

Depending on the syndrome, testing may be performed on:

• Cerebrospinal fluid

• Respiratory specimens

• Stool

• Blood

• Vesicular or other lesion specimens

For suspected enteroviral meningitis, molecular detection from CSF can be particularly useful.

Treatment

Treatment is primarily:

Symptomatic and supportive

Management depends on the clinical syndrome and severity of infection.

Antiviral Therapy

The source states:

There is no effective specific antiviral treatment routinely available.

Supportive management may include hydration, analgesia, fever control, neurologic monitoring, and intensive care when severe CNS or cardiopulmonary complications occur.

Prevention

Good hygiene is important because enteroviruses can spread through contaminated hands, surfaces, respiratory secretions, and fecal material.

Preventive measures include:

• Frequent handwashing

• Appropriate sanitation

• Cleaning contaminated surfaces

• Avoiding close contact during contagious illness

• Avoiding sharing personal items

Conjunctivitis Prevention

During outbreaks of acute hemorrhagic conjunctivitis:

Do not share towels or other personal items that contact the eyes or face.

This helps prevent indirect transmission of the virus between individuals.

High-Yield Clinical Pattern – Enterovirus 70

Very short incubation of 12–72 hours

• ●

Rapid-onset conjunctivitis

• ●

Subconjunctival hemorrhage

→ Think Enterovirus 70

High-Yield Clinical Pattern – Enterovirus A71

Young child

• ●

Hand-foot-and-mouth disease or rash

• ●

Encephalitis or acute flaccid paralysis

→ Think Enterovirus A71

Exam Essentials

Group: Enterovirus

Family: Picornaviridae

Genome: Positive-sense single-stranded RNA

Envelope: Absent (naked)

Capsid: Icosahedral

Distribution: Worldwide

Frequency: Common

Major transmission: Fecal–oral; some also spread through respiratory/contact routes

EV-70: Acute hemorrhagic conjunctivitis

EV-70 incubation: 12–72 hours

EV-A71: Hand-foot-and-mouth disease + neurologic disease

Neurologic manifestations: Meningitis, encephalitis, acute flaccid paralysis

Diagnosis: Molecular testing, with culture and serology in selected settings

Treatment: Supportive

Specific routine antiviral treatment: None

Conjunctivitis prevention: Avoid sharing towels and other potentially contaminated personal items

Historical terminology: Hepatitis A was formerly called enterovirus 72 but is now classified as a Hepatovirus

Key clinical pearl: Remember EV-70 → acute hemorrhagic conjunctivitis, while EV-A71 → hand-foot-and-mouth disease with potential severe neurologic complications such as encephalitis and poliomyelitis-like acute flaccid paralysis.

Medicine – Reduced or Absent Glucose in CSF

Low cerebrospinal fluid (CSF) glucose, or hypoglycorrhachia, is an important clue in the investigation of meningitis and meningeal disease. CSF glucose should ideally be interpreted in relation to a simultaneous blood glucose, because the absolute CSF value alone can be misleading.

A reduced CSF glucose level is especially associated with bacterial meningitis, tuberculous meningitis, fungal meningitis, and malignant infiltration of the meninges.

1. Bacterial Meningitis

Acute bacterial meningitis is one of the classic causes of markedly reduced CSF glucose.

The typical CSF pattern is:

Neutrophils ↑↑ + protein ↑↑ + glucose ↓↓.

The low glucose results from a combination of increased glucose consumption by inflammatory cells and microorganisms, together with impaired transport of glucose across the inflamed blood-CSF barrier.

2. Tuberculous Meningitis

Tuberculous meningitis also classically produces low CSF glucose.

The characteristic pattern is:

Lymphocytes ↑ + protein ↑↑↑ + glucose ↓↓.

This can help distinguish TB meningitis from typical viral meningitis, where CSF glucose is usually normal.

Therefore:

Lymphocytes + low glucose → think TB or fungal meningitis rather than uncomplicated viral meningitis.

3. Malignant Meningitis

Malignant meningitis, also called leptomeningeal carcinomatosis or leptomeningeal metastasis, can produce reduced CSF glucose.

This occurs when malignant cells infiltrate the leptomeninges and interfere with normal CSF metabolism and transport.

Associated findings may include:

Raised CSF protein.

Increased opening pressure.

Abnormal CSF cytology.

Variable white-cell elevation.

Diagnosis often relies on CSF cytology and contrast-enhanced MRI, sometimes requiring repeated CSF sampling.

4. Fungal Meningitis

Fungal meningitis is another important cause of low CSF glucose.

The CSF often resembles TB meningitis:

Lymphocytes/mononuclear cells ↑ + protein ↑ + glucose ↓.

A particularly important example is cryptococcal meningitis, especially in immunocompromised patients.

Opening pressure may also be markedly elevated in cryptococcal meningitis.

5. Mumps Meningitis

The original notes list mumps as an atypical cause.

Mumps can cause viral meningitis, but this needs qualification.

Most viral meningitides have a normal CSF glucose, and mumps is one of the viral infections in which CSF glucose can occasionally be reduced.

Therefore, mumps should be remembered as an exception rather than a typical cause of severe hypoglycorrhachia.

6. Other Causes

Other conditions can also lower CSF glucose.

These include some chronic infections, certain inflammatory meningeal diseases, and occasionally severe neurosarcoidosis.

However, the major examination causes remain:

Bacterial meningitis.

TB meningitis.

Fungal meningitis.

Malignant meningitis.

7. CSF-to-Blood Glucose Ratio

The CSF glucose value is best interpreted alongside plasma glucose.

Normally:

CSF glucose ≈ 60–70% of plasma glucose.

A reduced CSF:plasma glucose ratio, particularly below about 0.4, supports pathological hypoglycorrhachia in the appropriate clinical setting.

8. Reduced CSF Glucose – Note Form

Bacterial meningitis: low glucose + neutrophils + high protein.

TB meningitis: low glucose + lymphocytes + very high protein.

Fungal meningitis: low glucose + lymphocytic/mononuclear response + high protein.

Malignant meningitis: low glucose + high protein ± malignant cells in CSF.

Mumps meningitis: viral meningitis usually has normal glucose, but mumps can occasionally lower it.

Key Clinical Pattern

Remember:

Low CSF glucose → bacterial, TB, fungal, or malignant meningitis.

A useful distinction is:

Neutrophils + low glucose → bacterial meningitis.

Lymphocytes + low glucose → TB or fungal meningitis.

Lymphocytes + normal glucose → typical viral meningitis.

Low glucose + malignant cells → leptomeningeal malignancy.

Medicine – Cerebrospinal Fluid (CSF) Findings

Cerebrospinal fluid (CSF) analysis is particularly useful when investigating meningitis, encephalitis, inflammatory neurological disease, and demyelinating disorders such as multiple sclerosis.

The major features to assess are opening pressure, appearance, glucose, protein, white-cell count and differential, microbiology, and—when appropriate—oligoclonal bands and other specialised tests.

A particularly useful examination pattern is:

Bacterial meningitis → neutrophils + low glucose + very high protein.

Viral meningitis → lymphocytes + normal glucose + moderately raised protein.

TB meningitis → lymphocytes + low glucose + high protein.

Multiple sclerosis → oligoclonal bands + raised IgG index, with glucose usually normal.

1. Normal CSF

Normal CSF is clear and colourless, often described as having a crystal-clear appearance.

There should be very few white blood cells, with normal adult CSF generally containing approximately 0–5 white cells/µL, predominantly mononuclear cells.

Normal CSF Glucose

CSF glucose is normally approximately 60–70% of the simultaneous plasma glucose concentration.

The image gives approximately one-half to two-thirds of blood glucose, which is a useful traditional approximation.

Interpretation is more reliable when CSF glucose is compared with a blood glucose measurement obtained around the time of lumbar puncture.

Normal CSF Protein

Normal CSF protein is relatively low.

The image gives approximately:

0.2–0.4 g/L.

Exact reference ranges vary according to the laboratory, patient age, and sampling site.

Normal CSF Opening Pressure

Opening pressure should be measured with the patient appropriately positioned, usually in the lateral decubitus position.

The image gives an older normal range of approximately 60–150 mmH₂O.

Modern adult reference ranges are often somewhat broader, with values around 60–250 mmH₂O frequently used depending on the clinical setting and measurement technique.

Therefore, opening pressure should always be interpreted in clinical context.

2. Acute Bacterial Meningitis

Acute bacterial meningitis produces an intense inflammatory response within the meninges and CSF.

The characteristic pattern is:

Turbid CSF + neutrophils ↑↑ + protein ↑↑ + glucose ↓.

Appearance

CSF may appear turbid or purulent because of the large number of inflammatory cells, organisms, and increased protein.

However, CSF appearance alone cannot reliably confirm or exclude bacterial meningitis.

Glucose

CSF glucose is characteristically low.

This reflects consumption of glucose by inflammatory cells and microorganisms together with impaired glucose transport across the inflamed blood-CSF barrier.

A low CSF-to-blood glucose ratio is particularly helpful.

Protein

CSF protein is usually markedly elevated because inflammation disrupts the blood-CSF barrier and allows increased protein to enter the CSF.

Therefore:

Bacterial meningitis → very high protein.

White Cells

The white-cell count is usually substantially increased, often into the hundreds or thousands of cells/µL.

The predominant cells are usually neutrophils (polymorphs).

The image gives approximately 200–3000 polymorphs/mm³, but exact counts vary widely and should not be treated as rigid diagnostic boundaries.

Microbiology

Important investigations include Gram staining and bacterial culture.

Modern assessment frequently also includes molecular/PCR-based testing, depending on local laboratory availability and the suspected organism.

Blood cultures should ideally be obtained because bacteraemia may accompany bacterial meningitis.

Opening Pressure

Opening pressure is commonly raised, although a normal opening pressure does not completely exclude bacterial meningitis.

3. Acute Viral Meningitis

Viral meningitis generally produces a less dramatic CSF disturbance than bacterial meningitis.

The classic pattern is:

Clear CSF + lymphocytes ↑ + protein mildly/moderately ↑ + glucose normal.

Appearance

CSF is usually clear, although mild turbidity can occasionally occur when the cell count is high.

Glucose

CSF glucose is usually normal.

This is one of the most useful differences between typical viral and bacterial meningitis.

Therefore:

Viral → normal glucose.

Bacterial → low glucose.

There are exceptions, so the complete clinical and laboratory picture remains important.

Protein

CSF protein is usually mildly to moderately elevated, rather than reaching the very high levels often seen in bacterial or tuberculous meningitis.

White Cells

A lymphocytic/mononuclear pleocytosis is characteristic.

The image gives approximately 10–100 mononuclear cells/mm³, although viral meningitis can produce substantially higher counts.

Early in some viral infections, particularly during the first hours of illness, neutrophils may temporarily predominate before the CSF becomes lymphocyte-predominant.

Microbiology

Modern diagnosis commonly relies on CSF PCR or other nucleic-acid amplification testing for relevant viruses.

Depending on the clinical presentation, organisms tested may include enteroviruses, HSV, VZV, and others.

Serological testing may occasionally have a role but is generally less useful than appropriate molecular testing for many acute CNS viral infections.

4. Tuberculous Meningitis

Tuberculous meningitis is caused by Mycobacterium tuberculosis infection of the meninges.

The characteristic CSF pattern is:

Lymphocytes ↑ + protein ↑↑ + glucose ↓ + opening pressure ↑.

This combination is extremely important for examinations.

Appearance

CSF may be clear, slightly cloudy, or occasionally described as viscous because of the increased protein and inflammatory material.

Historically, CSF left standing could form a delicate “cobweb” clot, although this is not relied upon in modern diagnosis.

Glucose

CSF glucose is usually low, often with a reduced CSF-to-blood glucose ratio.

This means TB meningitis shares low CSF glucose with bacterial meningitis.

Protein

Protein is usually markedly elevated.

Very high CSF protein can occur, particularly when inflammation is severe or CSF flow is impaired.

White Cells

The typical cellular response is lymphocytic/mononuclear pleocytosis.

The image gives approximately 100–300 mononuclear cells/mm³, but considerable overlap occurs.

Importantly, early TB meningitis can occasionally show a more neutrophilic pattern before becoming predominantly lymphocytic.

Microbiology

The image lists acid-fast bacilli using Ziehl–Neelsen staining.

This is correct historically, but direct AFB microscopy has limited sensitivity.

Modern investigation may include:

Mycobacterial culture.

Nucleic-acid amplification/PCR-based testing.

AFB microscopy.

Larger-volume CSF samples can improve microbiological yield.

Opening Pressure

Opening pressure is commonly raised in tuberculous meningitis.

This can result from meningeal inflammation and impaired CSF circulation or absorption, sometimes leading to hydrocephalus.

5. Multiple Sclerosis

CSF analysis in multiple sclerosis (MS) differs considerably from meningitis because MS is a chronic immune-mediated demyelinating disorder rather than a meningeal infection.

Routine CSF appearance and glucose are generally normal.

The major abnormalities involve intrathecal immunoglobulin production.

Appearance

CSF is usually:

Clear and normal in appearance.

Glucose

CSF glucose is generally:

Normal.

A substantially reduced CSF glucose concentration would suggest an alternative diagnosis rather than typical MS.

Protein

Total protein may be normal or mildly elevated.

The image simply describes protein as high, but marked protein elevation is not characteristic of uncomplicated MS and should prompt consideration of another process.

White Cells

CSF may be completely normal or show a mild mononuclear/lymphocytic pleocytosis.

A large white-cell count is unusual and should raise suspicion for infection or another inflammatory neurological disorder.

The image gives 5–50 mononuclear cells/mm³, but typical MS often has fewer cells, and counts above roughly 50 cells/µL would be atypical.

6. Oligoclonal Bands

The classic CSF finding in MS is the presence of CSF-restricted oligoclonal IgG bands.

These indicate intrathecal immunoglobulin synthesis.

The important concept is not simply that oligoclonal bands are “positive,” but that bands are present in CSF in a pattern demonstrating intrathecal production when compared with serum.

7. IgG Index

The CSF IgG index may also be elevated in MS, reflecting increased production of immunoglobulin within the central nervous system.

However, modern diagnosis places substantial importance on CSF-specific oligoclonal bands, interpreted alongside MRI and the clinical presentation.

Neither oligoclonal bands nor an elevated IgG index is completely specific for MS.

8. Normal CSF – Note Form

Appearance: clear and colourless.

Glucose: approximately 60–70% of simultaneous plasma glucose.

Protein: low, approximately 0.2–0.4 g/L in the older reference shown; laboratory ranges vary.

White cells: approximately 0–5 cells/µL.

Opening pressure: depends on technique and patient factors; the older 60–150 mmH₂O range is narrower than many modern adult reference ranges.

9. Acute Bacterial Meningitis – Note Form

Appearance: turbid or purulent.

Glucose: ↓↓↓.

Protein: ↑↑↑.

White cells: markedly ↑.

Predominant cell: neutrophils/polymorphs.

Microbiology: Gram stain, bacterial culture and appropriate molecular testing.

Opening pressure: often ↑.

10. Viral Meningitis – Note Form

Appearance: usually clear.

Glucose: usually normal.

Protein: mildly/moderately ↑.

White cells: ↑.

Predominant cell: lymphocytes/mononuclear cells.

Early disease: neutrophils may occasionally predominate initially.

Microbiology: viral PCR/nucleic-acid testing where appropriate.

Opening pressure: normal or mildly ↑.

11. TB Meningitis – Note Form

Appearance: clear to slightly cloudy; may have increased viscosity.

Glucose: ↓↓↓.

Protein: ↑↑↑.

White cells: ↑.

Predominant cell: lymphocytes/mononuclear cells.

Microbiology: mycobacterial culture + molecular testing ± AFB staining.

Opening pressure: commonly ↑.

12. Multiple Sclerosis – Note Form

Appearance: normal/clear.

Glucose: normal.

Protein: normal or mildly ↑.

White cells: usually normal or mildly increased.

Predominant cells when increased: mononuclear/lymphocytic.

Key finding: CSF-restricted oligoclonal IgG bands.

IgG index: may be ↑.

Opening pressure: usually normal; a significantly raised pressure suggests another or additional diagnosis.

Key Clinical Pattern

The easiest way to remember the CSF patterns is:

Bacterial meningitis

Neutrophils ↑↑↑ + protein ↑↑↑ + glucose ↓↓↓

Viral meningitis

Lymphocytes ↑ + protein ↑ + glucose NORMAL

TB meningitis

Lymphocytes ↑↑ + protein ↑↑↑ + glucose ↓↓↓

Multiple sclerosis

Oligoclonal IgG bands + raised IgG index ± mild lymphocytosis; glucose NORMAL

High-Yield Distinction

Low CSF glucose → think bacterial or TB meningitis.

Normal CSF glucose + lymphocytes → think viral meningitis.

Neutrophils + low glucose → strongly suggests bacterial meningitis.

Lymphocytes + low glucose + very high protein → strongly suggests TB meningitis.

Oligoclonal bands → strongly associated with MS, but not completely specific.

Medicine – Eye Signs in Medical Disorders

The eyes can provide important clues to systemic disease. Characteristic abnormalities of the conjunctiva, sclera, cornea, iris, and retina may point toward nutritional deficiencies, inherited connective-tissue disorders, metabolic disease, neurological conditions, infection, or malignancy.

The signs in your images include Bitot spots, blue sclera, Brushfield spots, corneal arcus, corneal calcification, Kayser–Fleischer rings, Lisch nodules, and Roth spots.

1. Bitot Spots

Bitot spots are superficial, foamy or whitish lesions that develop on the conjunctiva, usually on the temporal side of the eye.

They are classically associated with vitamin A deficiency and represent conjunctival epithelial keratinisation as part of xerophthalmia.

Vitamin A is essential for normal retinal function and maintenance of healthy epithelial surfaces.

Deficiency can initially produce night blindness, followed by conjunctival and corneal abnormalities.

The progression of severe vitamin A deficiency may include:

Night blindness → conjunctival xerosis → Bitot spots → corneal xerosis → keratomalacia → blindness.

Key association:

Bitot spots → vitamin A deficiency.

2. Blue Sclera

Blue sclera occurs when the sclera is abnormally thin or structurally altered, allowing the underlying dark uveal tissue to become more visible through it.

This gives the normally white sclera a characteristic blue or blue-grey appearance.

3. Osteogenesis Imperfecta

The classic systemic association with blue sclera is osteogenesis imperfecta.

Osteogenesis imperfecta is an inherited connective-tissue disorder, usually involving abnormalities of type I collagen.

Typical features include:

Recurrent fractures + blue sclerae + hearing impairment ± dentinogenesis imperfecta.

The blue appearance occurs because abnormal collagen produces a relatively thin sclera through which the underlying choroidal pigment becomes more visible.

For examinations:

Blue sclera → think osteogenesis imperfecta first.

4. Ehlers–Danlos Syndrome

Some forms of Ehlers–Danlos syndrome may also produce scleral abnormalities because of defective connective tissue.

Associated systemic features can include joint hypermobility, abnormal skin elasticity, tissue fragility, and easy bruising, depending on the subtype.

5. Marfan Syndrome

The image also lists Marfan syndrome with blue sclera.

Marfan syndrome certainly has important ocular manifestations, but blue sclera is not its classic eye sign.

The major ocular association to remember for Marfan syndrome is ectopia lentis, usually with superotemporal lens displacement.

Therefore:

Marfan syndrome → ectopia lentis is considerably more important for examinations than blue sclera.

6. Pseudoxanthoma Elasticum

Pseudoxanthoma elasticum is a connective-tissue disorder involving abnormal mineralisation and fragmentation of elastic fibres.

Its classic ocular manifestation is angioid streaks in the retina rather than blue sclera.

Angioid streaks represent breaks in a pathologically altered Bruch membrane.

Therefore:

Pseudoxanthoma elasticum → angioid streaks is the more useful association.

7. Hyperthyroidism

The image also includes hyperthyroidism under blue sclera, but this is not a major modern examination association.

The characteristic ocular findings of Graves disease include:

Proptosis.

Lid retraction.

Lid lag.

Restricted extraocular movement.

Exposure keratopathy in severe disease.

Therefore:

Hyperthyroidism/Graves → proptosis + lid retraction, rather than blue sclera, is the pattern to remember.

8. Brushfield Spots

Brushfield spots are small white or grey-white speckles around the peripheral iris.

They represent areas of stromal connective tissue within the iris.

They are classically associated with Down syndrome, although similar iris speckling can occasionally occur in individuals without Down syndrome.

For examinations:

Brushfield spots → Down syndrome.

9. Down Syndrome and the Eye

Down syndrome can have several additional ophthalmological associations.

These include refractive errors, strabismus, cataracts, keratoconus, and other ocular abnormalities.

However, Brushfield spots remain one of the classic physical examination associations.

10. Corneal Arcus

Corneal arcus is a grey-white or whitish ring of lipid deposition around the peripheral cornea.

It is produced by deposition of cholesterol and other lipids within the corneal stroma.

11. Arcus Senilis

In older adults, corneal arcus is extremely common and is known as arcus senilis.

In this setting it is generally an age-related finding and does not necessarily indicate pathological hypercholesterolaemia.

Therefore:

Older patient + corneal arcus → often normal age-related finding.

12. Corneal Arcus in a Young Patient

Corneal arcus is more significant when it develops in a young person.

Premature corneal arcus should raise suspicion for significant dyslipidaemia, particularly familial hypercholesterolaemia.

The older note specifically refers to type IIa and IIb hyperlipoproteinaemia, but modern practice usually focuses on the patient’s lipid profile and the possibility of an inherited lipid disorder.

Therefore:

Young patient + corneal arcus → check for hypercholesterolaemia.

13. Corneal Calcification

Calcium deposition in the superficial cornea can produce band keratopathy, which appears as a horizontal band of calcium across the exposed interpalpebral region of the cornea.

It is associated with both chronic ocular inflammation and disorders causing hypercalcaemia.

14. Hyperparathyroidism

Hyperparathyroidism can produce hypercalcaemia.

Persistent elevation of serum calcium can contribute to calcium deposition in ocular tissues, including the cornea.

Therefore:

Hyperparathyroidism → hypercalcaemia → corneal calcium deposition/band keratopathy.

15. Chronic Kidney Disease

The older term chronic renal failure is now generally described as chronic kidney disease (CKD) when discussing the broader condition.

Advanced CKD can profoundly disturb calcium, phosphate, parathyroid hormone, and vitamin D metabolism.

These abnormalities may contribute to ectopic calcium deposition, including corneal or conjunctival calcification.

16. Vitamin D Excess

Excessive vitamin D can cause hypercalcaemia, which may promote calcium deposition in tissues.

Therefore, severe vitamin D toxicity can contribute to corneal calcification.

17. Sarcoidosis

Sarcoidosis can disturb calcium metabolism because activated macrophages within granulomas increase production of active vitamin D.

This can produce:

↑ Vitamin D activation → ↑ intestinal calcium absorption → hypercalcaemia/hypercalciuria.

However, the classic ocular manifestation of sarcoidosis remains uveitis, rather than corneal calcification.

18. Kayser–Fleischer Rings

Kayser–Fleischer rings are brown, golden-brown, or greenish rings caused by copper deposition in Descemet membrane of the cornea.

They are classically associated with Wilson disease.

19. Wilson Disease

Wilson disease is an autosomal recessive disorder of copper metabolism, caused by pathogenic variants involving ATP7B.

Impaired biliary copper excretion leads to progressive copper accumulation, particularly in the:

Liver.

Brain.

Cornea.

Kayser–Fleischer rings are particularly common in patients with neurological manifestations of Wilson disease.

They are best detected by slit-lamp examination.

Key association:

Kayser–Fleischer rings → Wilson disease → copper deposition.

20. Lisch Nodules

Lisch nodules are small, well-defined, pigmented iris hamartomas.

They are strongly associated with neurofibromatosis type 1 (NF1).

They usually do not significantly impair vision themselves but provide an important diagnostic clue.

21. Neurofibromatosis Type 1

NF1 is an autosomal dominant disorder associated with pathogenic variants of the NF1 tumour-suppressor gene.

Other important features include:

Café-au-lait macules.

Axillary or inguinal freckling.

Cutaneous neurofibromas.

Plexiform neurofibromas.

Lisch nodules.

Optic pathway glioma.

Therefore:

Lisch nodules → NF1.

Do not confuse Lisch nodules with optic pathway gliomas; both can occur in NF1, but Lisch nodules are benign iris hamartomas.

22. Roth Spots

Roth spots are retinal haemorrhages with pale or white centres.

They are traditionally associated with infective endocarditis, particularly in older teaching with subacute bacterial endocarditis.

However, they are not specific for infective endocarditis.

23. Infective Endocarditis

Roth spots may occur in infective endocarditis as part of its systemic vascular and immunological manifestations.

Other classical findings can include splinter haemorrhages, Janeway lesions, Osler nodes, and systemic embolic phenomena, although these are not present in every patient.

For examinations:

Roth spots + fever + murmur → consider infective endocarditis.

24. Leukaemia

Leukaemia can also produce Roth spots and other retinal haemorrhages.

Retinal abnormalities can result from anaemia, thrombocytopenia, hyperviscosity, vascular injury, or infiltration related to the underlying haematological malignancy.

Therefore, a white-centred retinal haemorrhage is not diagnostic of infection.

25. Diabetes Mellitus

The image also lists diabetes as an association with Roth spots.

White-centred retinal haemorrhages can occasionally occur in diabetes, but the much more characteristic diabetic retinal findings are:

Microaneurysms.

Dot-and-blot haemorrhages.

Hard exudates.

Cotton-wool spots.

Venous beading and IRMA in severe NPDR.

Neovascularisation in proliferative disease.

26. Eye Signs – Note Form

Bitot spots → vitamin A deficiency.

Bitot spots are foamy conjunctival lesions caused by xerophthalmia.

Blue sclera → osteogenesis imperfecta.

The underlying uveal pigment becomes more visible through abnormal/thin scleral connective tissue.

Brushfield spots → Down syndrome.

These are small white or grey-white spots around the iris.

Corneal arcus in an older adult → commonly age-related.

Corneal arcus in a young patient → consider hypercholesterolaemia/familial dyslipidaemia.

Corneal calcification/band keratopathy → consider hypercalcaemia and chronic ocular inflammation.

Potential systemic associations include hyperparathyroidism and disorders of calcium metabolism.

Kayser–Fleischer rings → Wilson disease.

They represent copper deposition in Descemet membrane.

Lisch nodules → neurofibromatosis type 1.

They are benign pigmented iris hamartomas.

Roth spots → white-centred retinal haemorrhages.

Classically associated with infective endocarditis, but they are not specific and can occur in haematological and systemic diseases.

27. High-Yield Associated Eye Signs

A few corrections to the older table are particularly useful for examinations:

Osteogenesis imperfecta → blue sclera.

Marfan syndrome → ectopia lentis, usually superotemporal.

Homocystinuria → ectopia lentis, classically inferonasal.

Pseudoxanthoma elasticum → angioid streaks.

Graves disease → proptosis + lid retraction + lid lag.

Sarcoidosis → uveitis.

Wilson disease → Kayser–Fleischer rings.

NF1 → Lisch nodules ± optic pathway glioma.

Down syndrome → Brushfield spots.

Vitamin A deficiency → Bitot spots + night blindness.

Key Clinical Pattern

The most useful one-line associations to memorise are:

Bitot spots → Vitamin A deficiency

Blue sclera → Osteogenesis imperfecta

Brushfield spots → Down syndrome

Young patient with corneal arcus → Hypercholesterolaemia

Kayser–Fleischer rings → Wilson disease

Lisch nodules → Neurofibromatosis type 1

Roth spots → Infective endocarditis classically, but not specifically

And three additional high-yield associations:

Marfan syndrome → superotemporal lens dislocation

Pseudoxanthoma elasticum → angioid streaks

Graves disease → proptosis + lid retraction

Medicine – Diabetic Eye Disease

Diabetic eye disease refers to a group of ocular complications caused by chronic diabetes mellitus, particularly diabetic retinopathy and diabetic macular oedema. Chronic hyperglycaemia damages the small vessels of the retina, producing increased vascular permeability, retinal ischaemia, haemorrhage, and eventually abnormal new-vessel formation.

Diabetic retinopathy remains an important cause of preventable visual impairment and blindness in working-age adults, although the exact ranking varies between populations and has changed with improved screening and treatment.

1. Pathophysiology

Long-standing hyperglycaemia damages retinal capillary endothelial cells and pericytes.

This produces two major pathological processes:

Capillary leakage → retinal oedema, haemorrhage and hard exudates.

Capillary closure → retinal ischaemia → VEGF production → neovascularisation.

These mechanisms explain the progression from early non-proliferative disease to proliferative diabetic retinopathy.

2. Modern Classification

The older terms background retinopathy and pre-proliferative retinopathy remain useful for examination notes, but modern classification generally describes these stages as non-proliferative diabetic retinopathy (NPDR).

The broad progression is:

Non-proliferative retinopathy → severe NPDR → proliferative diabetic retinopathy.

Diabetic macular oedema can occur at various stages and is considered separately because it directly threatens central vision.

3. Background Diabetic Retinopathy

Background retinopathy represents relatively early retinal microvascular disease.

Visual acuity is often unaffected, particularly when the macula is not involved.

Typical abnormalities include:

Microaneurysms.

Retinal haemorrhages.

Hard exudates.

4. Microaneurysms

Microaneurysms are small outpouchings of weakened retinal capillary walls and are among the earliest clinically visible abnormalities of diabetic retinopathy.

On fundoscopy they appear as tiny red dots.

Their presence reflects diabetic retinal microvascular injury.

5. Retinal Haemorrhages

Damaged retinal microvessels can leak blood into the retina.

Haemorrhages may appear as dot-and-blot haemorrhages when located within deeper retinal layers.

Superficial haemorrhages may have a flame-shaped appearance, although flame haemorrhages are also commonly associated with other retinal vascular disorders.

6. Hard Exudates

Hard exudates are yellow-white deposits composed largely of lipid and protein material that has leaked from abnormal retinal vessels.

They frequently occur close to areas of microvascular leakage.

When they involve or surround the macula, they may indicate clinically important macular disease.

7. Vision in Background Retinopathy

An important clinical point is that significant retinal abnormalities may exist while the patient still has normal visual acuity.

Therefore, patients cannot rely on symptoms to detect early diabetic retinopathy.

This is why regular retinal screening is essential.

8. Pre-Proliferative Diabetic Retinopathy

The traditional term pre-proliferative retinopathy describes more severe non-proliferative retinal disease with increasing evidence of retinal ischaemia.

Important findings include:

Cotton-wool spots.

Venous dilatation and venous beading.

Intraretinal microvascular abnormalities (IRMA).

These findings indicate an increased risk of progression to proliferative disease.

9. Cotton-Wool Spots

Cotton-wool spots are fluffy white retinal lesions caused by focal ischaemia of the retinal nerve fibre layer.

They represent disruption of axoplasmic transport following microvascular occlusion.

Therefore:

Cotton-wool spots = retinal microinfarcts.

They are not specific to diabetes and can also occur in hypertension and several other vascular or systemic diseases.

10. Venous Beading

Venous beading refers to irregular changes in the calibre of retinal veins, producing alternating areas of narrowing and dilatation.

It is an important marker of significant retinal ischaemia and severe NPDR.

Increasing venous abnormalities indicate a greater risk of progression to proliferative diabetic retinopathy.

11. Intraretinal Microvascular Abnormalities

Intraretinal microvascular abnormalities (IRMA) are abnormal intraretinal vascular channels that develop in areas of retinal capillary non-perfusion.

They represent attempts to provide collateral circulation around areas of ischaemic retina.

IRMA remain within the retina, which helps distinguish them from true neovascularisation extending onto the retinal or vitreous surface.

12. Proliferative Diabetic Retinopathy

Proliferative diabetic retinopathy (PDR) is characterised by the development of new abnormal retinal blood vessels.

The underlying stimulus is severe retinal ischaemia.

Ischaemic retinal tissue releases angiogenic factors, particularly vascular endothelial growth factor (VEGF).

The sequence is:

Retinal capillary closure → retinal hypoxia → ↑ VEGF → neovascularisation.

13. Neovascularisation

New vessels may develop on or near the optic disc or elsewhere on the retina.

These vessels are structurally fragile and grow along abnormal tissue planes.

Unlike normal retinal vessels, they are particularly prone to bleeding and fibrosis.

This creates the major complications of proliferative diabetic retinopathy.

14. Type 1 and Type 2 Diabetes

Proliferative retinopathy has traditionally been particularly associated with long-standing type 1 diabetes, whereas diabetic macular disease is often emphasised in type 2 diabetes.

However, both PDR and diabetic macular oedema can occur in either type 1 or type 2 diabetes.

The major determinants include duration of diabetes, glycaemic control, blood pressure, renal disease and other vascular risk factors, rather than diabetes type alone.

15. Panretinal Photocoagulation

Patients who have undergone treatment for proliferative diabetic retinopathy may have visible panretinal photocoagulation (PRP) scars on fundoscopic examination.

PRP applies multiple laser burns to the peripheral retina.

By reducing the metabolic demand of ischaemic peripheral retinal tissue, it reduces the angiogenic drive and lowers VEGF production.

The aim is to cause regression of dangerous neovascularisation and reduce the risk of severe visual loss.

16. Advanced Diabetic Eye Disease

Untreated or progressive proliferative diabetic retinopathy can lead to advanced diabetic eye disease.

Important complications include:

Vitreous haemorrhage.

Tractional retinal detachment.

Neovascular, or rubeotic, glaucoma.

These complications can cause profound visual loss.

17. Vitreous Haemorrhage

Fragile new vessels can rupture and bleed into the vitreous cavity.

A vitreous haemorrhage may produce:

Sudden painless visual loss.

Floaters.

Cobweb-like shadows.

Hazy or severely obscured vision.

The degree of visual impairment depends on the amount of bleeding.

18. Tractional Retinal Detachment

Neovascularisation is accompanied by growth of fibrovascular tissue.

As this tissue contracts, it pulls mechanically on the retina.

The sequence is:

Neovascularisation → fibrovascular proliferation → contraction → traction on retina → tractional retinal detachment.

If the macula becomes detached, severe central visual loss may result.

19. Rubeosis Iridis

Severe retinal ischaemia can stimulate abnormal new blood vessels to grow on the iris.

This is called rubeosis iridis.

These vessels may subsequently extend into the anterior chamber drainage angle.

20. Rubeotic or Neovascular Glaucoma

Neovascularisation of the iris and drainage angle can obstruct aqueous humour outflow.

This causes marked elevation of intraocular pressure and produces neovascular glaucoma, historically called rubeotic glaucoma.

It can be painful, difficult to treat, and potentially devastating to vision.

21. Diabetic Maculopathy

Diabetic maculopathy refers to diabetic retinal disease involving the macula, the part of the retina responsible for detailed central vision.

A major manifestation is diabetic macular oedema (DMO/DME).

Damage to retinal capillaries increases vascular permeability, allowing fluid and lipid to accumulate within the macula.

22. Macular Oedema

Fluid accumulation causes thickening and swelling of the macula.

Because the macula is responsible for high-resolution central vision, macular oedema may cause:

Blurred central vision.

Difficulty reading.

Reduced fine visual detail.

Distortion of central images.

23. Hard Exudates at the Macula

Vascular leakage can also produce hard exudates around the macula.

These lipid deposits may form circinate patterns around leaking microaneurysms.

The original notes refer to multiple exudates as a macular star. A true macular-star pattern can occur with retinal vascular leakage but is not specific to diabetic retinopathy and is classically associated with disorders such as neuroretinitis and severe hypertensive disease.

24. Central versus Peripheral Vision

Macular disease predominantly damages central vision because the macula provides detailed central visual acuity.

Peripheral vision may initially remain relatively preserved.

Therefore:

Diabetic macular oedema → central visual loss.

By contrast, extensive peripheral retinal photocoagulation can reduce peripheral visual field and night vision as a trade-off for preventing more severe vision-threatening complications.

Treatment

25. Good Glycaemic Control

Good long-term glycaemic control is fundamental to preventing and slowing diabetic retinopathy.

Persistent hyperglycaemia increases retinal microvascular injury.

Therefore, reducing long-term glucose exposure reduces the risk of developing and progressing diabetic microvascular complications.

26. Blood Pressure Control

Hypertension accelerates retinal microvascular damage.

Effective blood-pressure management is therefore an important component of diabetic eye protection.

The patient should be managed for overall cardiovascular and renal risk rather than treating the eye in isolation.

27. Lipid Management

Abnormal serum lipid levels are associated with retinal vascular disease and hard exudate formation.

Appropriate management of dyslipidaemia/hypercholesterolaemia is therefore part of comprehensive diabetes care.

28. Smoking Cessation

Patients should be encouraged to stop smoking because smoking substantially increases overall cardiovascular and microvascular risk.

Smoking cessation also benefits the patient’s renal, neurological, and cardiovascular health.

29. Regular Retinal Screening

Regular retinal assessment is essential because diabetic retinopathy can become significant before the patient notices visual symptoms.

Depending on the healthcare system, screening may use digital retinal photography, dilated fundal examination, optical coherence tomography (OCT), or specialist ophthalmological assessment.

OCT is particularly valuable for detecting and quantifying diabetic macular oedema.

30. Focal or Grid Laser Treatment

Focal or grid retinal laser photocoagulation has historically been important in the treatment of diabetic macular oedema.

Laser can target leaking microaneurysms or areas of retinal thickening in selected situations.

However, management of diabetic macular oedema has changed substantially with the development of intravitreal therapy.

31. Anti-VEGF Therapy

An important modern addition to the original notes is intravitreal anti-VEGF therapy.

Agents targeting VEGF can reduce vascular leakage, macular oedema, and pathological neovascularisation.

Anti-VEGF therapy is now central to the treatment of many patients with centre-involving diabetic macular oedema and is also used in the management of proliferative diabetic retinopathy in appropriate circumstances.

32. Panretinal Photocoagulation

Panretinal photocoagulation (PRP) remains an important treatment for proliferative diabetic retinopathy.

Numerous laser burns are applied to the peripheral retina.

The objective is not to improve normal peripheral retina but to reduce the stimulus for pathological neovascularisation and thereby prevent catastrophic complications such as vitreous haemorrhage and tractional retinal detachment.

33. Vitrectomy

Advanced disease may require vitrectomy surgery.

Indications can include persistent or severe vitreous haemorrhage and tractional retinal detachment threatening or involving the macula.

During surgery, vitreous haemorrhage and abnormal fibrovascular tissue can be removed and retinal anatomy addressed as appropriate.

34. Diabetic Retinopathy – Note Form

Background/non-proliferative retinopathy: visual acuity may remain normal.

Microaneurysms: tiny red capillary outpouchings and an early visible sign.

Haemorrhages: commonly dot-and-blot retinal haemorrhages.

Hard exudates: yellow-white lipid deposits caused by vascular leakage.

Pre-proliferative/severe NPDR: increasing retinal ischaemia without true new-vessel formation.

Cotton-wool spots: retinal nerve fibre layer microinfarcts.

Venous beading: irregular retinal venous calibre indicating significant retinal ischaemia.

IRMA: abnormal intraretinal vascular channels associated with capillary non-perfusion.

Proliferative retinopathy: defined by neovascularisation.

Mechanism of proliferation: retinal ischaemia → increased VEGF → abnormal new vessels.

Advanced disease: vitreous haemorrhage, tractional retinal detachment and neovascular glaucoma.

Diabetic macular oedema: vascular leakage into the macula → impaired central vision.

Systemic management: optimise glycaemic control, blood pressure and lipid management and encourage smoking cessation.

Monitoring: regular diabetic retinal screening, with OCT when macular disease needs assessment.

Modern ocular treatment: anti-VEGF injections, laser treatment where appropriate, PRP for proliferative disease, and vitrectomy for selected advanced complications.

Key Clinical Pattern

Remember the progression as:

Microaneurysms → haemorrhages/exudates → cotton-wool spots + venous beading + IRMA → neovascularisation → vitreous haemorrhage/tractional retinal detachment.

The most important distinction is:

Non-proliferative diabetic retinopathy → abnormal existing retinal vessels.

Proliferative diabetic retinopathy → NEW vessels.

And remember:

Macular oedema → central visual loss.

Proliferative retinopathy → neovascularisation → vitreous haemorrhage + tractional retinal detachment + neovascular glaucoma.

A useful treatment pattern is:

Risk-factor control + screening → anti-VEGF for many cases of diabetic macular oedema → PRP for proliferative retinopathy → vitrectomy for selected advanced disease.

Medicine – Hypertensive Retinopathy

Hypertensive retinopathy refers to retinal vascular changes caused by systemic arterial hypertension. Persistent high blood pressure damages the retinal arterioles, leading first to vasoconstriction and vessel-wall thickening, and in more severe disease to retinal ischaemia, haemorrhage, exudation, and optic-disc swelling.

The traditional grading system runs from Grade 1 to Grade 4, with increasing severity of retinal damage.

1. Grade 1 Hypertensive Retinopathy

Grade 1 disease represents relatively early vascular change.

The main abnormality is generalised arteriolar narrowing, reflecting vasoconstriction and early vessel-wall thickening.

The retinal arterioles may also show an increased light reflex, giving the vessel a brighter appearance.

2. Silver Wiring

Your note places silver wiring in Grade 1, but this is better thought of as a sign of more advanced arteriolar sclerosis.

As the arteriolar wall thickens, the normal blood-column reflex becomes increasingly prominent.

This progression is traditionally described as:

Copper wiring → silver wiring.

Copper wiring reflects moderate thickening and increased arteriolar light reflex.

Silver wiring reflects more severe sclerosis, where the vessel wall becomes so opaque that the blood column is difficult to see.

Therefore, silver wiring is a useful hypertensive/arteriosclerotic retinal sign, but it is not necessarily confined strictly to Grade 1.

3. Grade 2 Hypertensive Retinopathy

Grade 2 includes more obvious arteriolar changes, particularly arteriovenous crossing abnormalities.

The classic feature is AV nipping, also called AV nicking.

4. Arteriovenous Nipping

At points where a retinal arteriole crosses over a retinal vein, both vessels share a common adventitial sheath.

With chronic hypertension, the arteriole becomes thickened and rigid.

This compresses the underlying vein at the crossing point, producing AV nicking or nipping.

Therefore:

Thickened arteriole → compression of retinal vein at crossing → AV nipping.

5. Focal Arteriolar Attenuation

Grade 2 disease may also show focal narrowing of retinal arterioles.

This reflects localized vasoconstriction and structural arteriolar damage.

Generalised narrowing plus focal attenuation indicates more established hypertensive vascular disease than Grade 1.

6. Grade 3 Hypertensive Retinopathy

Grade 3 represents more severe retinal vascular injury and is associated with breakdown of the blood-retinal barrier and retinal ischaemia.

The important features are:

Retinal haemorrhages.

Hard exudates.

Cotton-wool spots.

These findings indicate significantly more severe hypertension and target-organ damage.

7. Retinal Haemorrhages

Retinal vascular damage can cause leakage of blood into the retina.

In hypertensive retinopathy, haemorrhages are commonly flame-shaped because blood tracks along the retinal nerve fibre layer.

Other patterns can occur depending on the depth of retinal involvement.

8. Hard Exudates

Hard exudates are yellow-white lipid deposits in the retina.

They result from leakage of plasma lipids and proteins through damaged retinal vessels.

They may accumulate around the macula in a radial pattern, producing a macular star in severe disease.

9. Cotton-Wool Spots

Cotton-wool spots are fluffy white retinal lesions caused by focal ischaemia of the retinal nerve fibre layer.

They represent interruption of axoplasmic transport following occlusion of small retinal arterioles.

Therefore:

Cotton-wool spots = retinal microinfarcts.

They are not specific to hypertension and may also occur in conditions such as diabetes, retinal vascular disease, HIV, and severe anaemia.

10. Grade 4 Hypertensive Retinopathy

Grade 4 represents the most severe form in the traditional classification.

It consists of the Grade 3 changes plus optic-disc swelling.

Historically this has often been described as papilloedema.

11. Optic-Disc Swelling in Severe Hypertension

In severe hypertensive emergency, the optic nerve head may become swollen as part of hypertensive optic neuropathy.

Older classifications call this “papilloedema,” but strictly speaking, papilloedema means optic-disc swelling caused by raised intracranial pressure.

Therefore, in modern terminology it is more accurate to say:

Grade 4 hypertensive retinopathy → severe retinopathy + optic-disc oedema.

If raised intracranial pressure is actually present, then the term papilloedema is appropriate.

12. Clinical Significance of Grade 4 Disease

Grade 4 hypertensive retinopathy usually indicates severe hypertension with acute target-organ injury.

This may occur in the context of a hypertensive emergency and requires urgent systemic assessment and blood-pressure management.

Associated complications may include encephalopathy, renal injury, cardiac failure, or other vascular damage.

13. Pathophysiological Progression

The progression can be remembered as:

Hypertension → arteriolar narrowing → vessel-wall sclerosis → AV crossing changes → retinal ischaemia/leakage → haemorrhages and exudates → optic-disc swelling in severe disease.

14. Hypertensive Retinopathy – Note Form

Grade 1: mild/generalised retinal arteriolar narrowing and increased arteriolar light reflex.

Copper/silver wiring: due to progressive arteriolar wall thickening; silver wiring represents more advanced sclerosis.

Grade 2: Grade 1 changes plus more obvious arteriolar damage, especially AV nicking/nipping and focal narrowing.

Grade 3: Grade 2 changes plus retinal haemorrhages, hard exudates and cotton-wool spots.

Grade 4: Grade 3 changes plus optic-disc swelling.

15. Quick Interpretation

Arteriolar narrowing → early hypertension.

AV nipping → chronic arteriolar sclerosis.

Haemorrhages + exudates + cotton-wool spots → severe hypertensive retinal injury.

Optic-disc swelling → very severe disease / hypertensive emergency.

Key Clinical Pattern

Remember the traditional sequence as:

Grade 1 → narrowing.

Grade 2 → AV nipping.

Grade 3 → haemorrhages + hard exudates + cotton-wool spots.

Grade 4 → optic-disc swelling.

A useful visual progression is:

Narrow vessels → crossing changes → retinal leakage/ischaemia → optic-disc oedema.