Fungus and Prions

Superficial mycosis

• infect skin, mucosa, hair, nails

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Subcutcaneous Mycosis

• infect skin and connective tissue

Systemic mycosis

• infects internal organs

• Opportunistic- seen mainly in immunocompromised hosts

• Non-opportunistic- can occur in any host

Dermatophytosis (tinea/ringworm)

• direct contact w/ people, animals, soil

• Release keratin-degrading enzymes and infect skin, hair, and nails

• Itchy, scaly, red lesions with a central clearing

• Common in IMC, use topical or oral -azole

Tinea corporis

• skin contact or contaminated objects

• Dermatophyte infection of body

• Scaly plaque w/ advancing border and clear clearing

• Topical antifungal (ringworm)

Tinea capitis

• person-person, animals

• Dermatophytes infect scalp hair and follicles

• scalp scaling, alopecia, inflammation

• Oral antifungal

Tinea pedis

• contaminated floors, shoes, socks

• Infection of feet

• Scaling, fissuring, burning and itching

• Topical antifungal

Tinea cruris

• direct contact, spread from tinea pedis

• Dermatophyte infection of the groin

• itchy, red, scaling groin rash w/ central clearing

• Topical antifungal

Tinea barbae

• infected animals

• Dermatophyte infection of beard follicles

• Inflammatory plaques, pustules, broken hairs

• Oral antifungals

Tinea unguium

• direct contact or spread from tinea pedis

• Dermatophyte invades the nail plate and nail bed

• Thick, brittle discolored nails

• oral antifungal, terbinafine

Tinea versicolor

• not contagious, overgrowth of fungus in fat layer

• Lipid-dependent yeast overgrows in the superficial stratum corneum and interferes with pigmentation

• Hypo or Hyper pigmentation of finely scaling patches on trunk or shoulders

• KOH: “spaghetti and meatballs”

• Topical azole

Cutaneous candidiasis

• overgrowth of pt own flora

• Lives in warm, moist skin folds

• Bright-red moist rash with satellite papules or pustules

• Topical azole or nystatin

Oral candidiasis (Thrush)

• overgrowth of own flora

• Candida adheres to and inflames oral mucosa can move to pharynx

• Painful white plaques that scrape off leaving red or bleeding base

• Oral antifungals

Vulvovaginal candidiasis

• overgrowth of own bacteria

• altered vaginal flora (antibiotics) allows Candida to proliferate and inflame

• very itchy, burning, red, thick cottage-cheese discharge, no odor

• Topical azole

Candidal Funguria

• UTI

• May cause hesitency, urgency, fever, chills, flank pain

• Yeast in urine of a catheterized or diabetic pt

Invasive Candida

• endogenous spread or entry through an IV catheter

• Enters blood to other organs

• Persistent fever, sepsis, multiorgan

• persistent fever/sepsis in a pt w/ central line

Candidal fungemia

• found on very ill pts w/ indwelling instrumentation

• IV is needed

Candida endocarditis

• Candida grows on prosthetic heart valves

• prosthetic valve + candidemia + large vegetations (mass of yeast)

Cryptococcus

• inhaled from soil contaminated w/ pigeon droppings

• Encapsulated budding yeast enters lungs → may disseminate to CNS, especially with impaired cell-mediated immunity

• Headache, fever, altered mental status, acute meningitis, painful productive cough

• IMC w/ acute meningitis outdoors

• Oral fluconazole

Pneumocystis (PCJ)

• airborne person-person exposure

• Organisms fill alveoli with foamy material → impaired gas exchange and severe hypoxemia

• progressive dyspnea, dry cough, fever, hypoxemia

• Beta-D-glucan test, IMC vulnerable

• AIDS + dry cough+ bilateral ground-glass/interstitial infiltrates

Histoplasmosis

• inhalation contamination w/ bird or bat droppings near Ohio and Mississippi River valleys

• Inhaled spores become yeast and survive inside macrophages → spread through reticuloendothelial system

• fever, cough, weight loss, disseminated can affect liver, spleen, bone marrow

• Intraconazole

• Ohio/Mississippi River valleys + bird/bat droppings + intracellular yeast in macrophages

Coccidiomycosis

• Inhalation of spores from desert soil in Southwest

• Inhaled arthroconidia become tissue spherules containing endospores → granulomatous pulmonary inflammation

• Fever, cough, sharp chest pain, erythema nodosum

• desert dust + valley fever + erythema nodosum and arthralgia

Prion Pathophys

• prion protein contacts a normal protein, converted into a beta-sheet-rich misfolded form, making insoluble amyloid-like fibrils, neuron damage leading to stress and cell death

• Spongiform encephalopathy

Sporadic CJD

• most common form

• rapid progressive dementia, myoclonus, ataxia, behavior and visual changes

• MRI, no cure, just hospice

• death within one year

Familiar CJD

• mutation of PRNP gene

• rapid progressive dementia, myoclonus, ataxia, behavior and visual changes

• Genetic testing and supportive care

• Family history of rapidly progressive fatal dementia

Acquired CJD

• contaminated neurosurgical instruments

• Progressive dementia, myoclonus, ataxia and neurologic deterioration

• MRI and lumbar puncture

• Symptoms after a cadaveric graft or pituitary-derived hormone

Variant CJD

• consumed contaminated beef

• begins with psych issues then dementia

• Younger pt w/ psych symptoms after exposure to contaminated beef

GSS Disease

• PRNP mutation

• Cerebellar ataxis then dementia and dysarthria

• Familial genetic counseling

Kuru

• consumption of infected human nervous tissue

• tremor, cerebellar ataxia, dysarthria, emotional change, dementia

• “laughing sickness”

Mad Cow Disease

• cattle get prion from contaminated feed

• neurologic degeneration in cattle

• Causes variant CJD in humans