Mycology Flashcards
Histoplasmosis
dimorphic fungi - cold = mold; heat = yeast
Mississippi and Ohio River valley
causes pneumonia
macrophages filled with Histoplama (smaller than RBCs)
bird or bat droppings
no person-to-person transmission
treatment: fluconazole or itraconazole for local infection; amphotericin B for systemic infections
Blastomycosis
dimorphic fungi - cold = mold; heat = yeast
states east of the Mississippi River and Central America
causes inflammatory lung disease and can disseminate to skin and bone
forms granulomatous nodules
broad-base budding (same size as RBC)
no person-to-person transmission
treatment: fluconazole or itraconazole for local infection; amphotericin B for systemic infections
Coccidioidomycosis
dimorphic fungi - cold = mold; heat = spherule
southwestern US, Cali
causes pneumonia and meningitis; can disseminate to bone and skin
case rate increase after earthquakes (spores in dust are thrown up in the air and become spherules in lungs)
spherule filled with endospores (much larger than RBCs)
San Joaquin or desert “valley fever”
no person-to-person transmission
treatment: fluconazole or itraconazole for local infection; amphotericin B for systemic infections
Paracoccidioidomycosis
dimorphic fungi - cold = mold; heat = yeast
Latin America
budding yeast with “captain’s wheel” formation (much larger than RBCs)
no person-to-person transmission
treatment: fluconazole or itraconazole for local infection; amphotericin B for systemic infections
Tinea versicolor
cutaneous mycoses - Malassezia furfur
“spaghetti and meatball” appearance on KOH prep
degradation of lipids produces acids that damage melanocytes and cause hypopigmentation and/or hyperpigmented patches
occurs in hot, humid weather
treatment: topical miconazole, selenium sulfide
Candida albicans
dimorphic yeast - cold = pseudohyphae and budding yeast, hot = germ tube
systemic or superficial fungal infection
oral and esophageal thrush in immunocompromised
vulvovaginitis (diabetes, use of antibiotics)
diaper rash
endocarditis in IV drug users
disseminated candidiasis (to any organ)
chronic mucocutaneous candidiasis
treatement:
topical azole for vaginal
fluconazole or caspofungin for oral/esophageal
fluconazole, amphotericin B, or caspofungin for systemic
Aspergillus fumigatus
septate hyphae that branch at 45 degree angle; conidiophore with radiating chains of spores
not dimorphic
invasive aspergillosis, especially in immunocompromised and those with chronic granulomatous disease
allergic bronchopulmonary aspergillosis: asthma or CF
aspergillomas in lung cavities, especially after TB infection
aflatoxin –> HCC
Cryptococcus neoformans
5-10 um yeasts with wide capsular halos and unequal budding in India ink stain
not dimorphic; heavily encapsulated yeast
cryptococcal meningitis, cryptococcosis
found in soil, pigeon droppings
acquired through inhalation with hematogenous dissemination to meninges
Sabouraud’s agar; latex agglutination test detects polysaccharide capsular antigen and is more specific
“soap bubble” lesions in brain
Mucor and Rhizopus spp.
irregular, broad, nonseptate, hyphae branching at wide angles
mucormycosis
most common in diabetic and leukemic patients
fungi proliferate in blood vessel walls when there is excess ketone and glucose –> penetrate cribriform plate and enter brain
rhinocerebral, frontal lobe abscesses
headache, facial pain, black necrotic eschar on face, may have CN involvement
Pneumocystis jirovecii
disc-shaped yeast on methenamine silver stain of lung tissue
most infections asymptomatic; pneumonia in AIDS
diffuse, bilateral CXR appearance
diagnosed by lung biopsy or lavage
treatment: TMP-SMX, pentamidine, dapsone; start prophylaxis when CD4 drops < 200 in HIV
Sporothrix schemckii
dimorphic, cigar-shaped budding yeast that lives on vegetation
spores traumatically introduced into the skin, typically by a thorn –> local pustule or ulcer with nodules along draining lymphatics
little systemic illness
treatment: itraconazole or potassium iodide
