Mycology Flashcards
Candida albicans
Normal flora - skin, GI, female genital tract
Scrape off leaves raw bleeding mucosa
Dx: blood culture: germ tubes - small projections on side of cell
Tx:
Superficial: Nystatin, clotrimazole, fluconazole
Systemic: fluconazole (normal immune), amphotericin B, Echinocandin
Oral thrush
white, curd like patches - top of tongue
immunocompromised - common in AIDS DM Chronic steroids Neonates inhales steroids
Candida vulvovaginitis
MC in DM, recent abx use
Sx: severe itching
edema
vaginal discharge
assoc w/ acidic pH
Candida diaper rash
erythematous skin, shines or eroded
edge of red area - jagged edge
satellite lesions - smaller, outside central lesion
Intertrigo
Candida infection under breast or skin folds of obese pts
erythematous central lesions w/ satellite lesions
Candida blood infections
central lines, drug users
Leads to:
endophthalmitis
Endocarditis
Chronic mucocutaneous candidiasis
inherent immune deficiency
molds considered dermatophytes
Trichophyton
Micosporum - dog/cat –> human
epidermophyton
malassezia furfur
Cryptococcus neoformans
AIDS: cryptococcal meningitis
heavily encapsulated yeast
reproduce by narrow-based budding
found in soil and pigeon droppings
cultured on most bacterial and fungal media
Sabouraud’s agar
India ink - stains everything but capsule - CSF and other specimens
Serologic test: cryptococcal ag
Latex agglutination test to detect polysaccharide capsular Ab
“Soap bubble” lesion in brain on imaging
Tx: amphotericin B + flucytosine, followed by fluconazole
Pneumocystis jirovecii
Yeast
PCP - diffuse interstitial pneumonia
potentially fatal in immunocompromised
Dx:
silver stain
imaging: ground glass appearing interstitial infiltrates
Tx: TMP-SMX
Sulfa allergy: pentamidine, clindamycin + primaquine
Severe + prednisone
Prophylaxis: CD4 under 200 - TMP-SMX
Aspergillus fumigatus
allergic bronchopulmonary aspergillosis
Fungus ball - aspergilloma
Invasive aspergillosis -immunocompromised
Ubiquitous fungus
Dx: narrow septet hyphae
branched at acute angles about 45 degrees
MOLD!
Tx: voriconazole, lipid formulation of amphotericin B
Mucor and Rhizopus
cause mucormycosis
-ubiquitous
Invasive dz:
severly immunocompromised
DM
trauma pt
Molds: broad, irregularly shaped nonseptate hyphae, branching right angles
flip M upside down to W = wide angle
Rhinocerebral mucormycosis
DM esp DKA and leukemia w/ neutropenia
head pain and HA
- -> large necrotic lesions like black eschar of palate/nose
- -> CN deficits, blindness
high mortality
Dx: bx
Tx: surgical debridement
Amphotericin B
Infections caused by dermatophytes
Tinea pedis - feet Tinea cruris - groin Tinea corporis - body Tinea capitis - head Dx: fungal hyphae or spores on skin or hair samples Cx
Tx: simple skin infections - topical terbinafine or azole
Extensive skin infections or scalp/hair: oral terbinafine or azole
Tinea unguium (nails) - nail plate, thickened, discolored nails
Tx: orally: terbinafine, itraconazole, fluconazole
-6wk - 6 mo for fingernails
-12 wks - 12 mo toe nails
Tinea versicolor
malassezia furor
lipophilic yeast –> hypo pigmented patches on body (or hyper)
-trunk and proximal limbs
small areas coalesce w/ scaling plaque
**KOH prep: spaghetti and meatballs appearance **
Treatment of mycoses
Localized uncomplicated infections: fluconazole, itraconazole
Severe, disseminated, complicated infections: amphotericin B
Systemic mycoses
Cause caseating and non-caseating granulomas
Cx on Sabouraud agar
Histoplasma capsulatum
Mississippi and Ohio river valleys
Bird and bat guano
Enters through lung, engulfed by N0 or M0
“Histo hides in M0”
Histo: M0 w/ hundreds of yeast forms in cystoplasm
Yeast – smaller than RBCs
Self limited pneumonia, minimal sx
Can become severe pneumonia or disseminated dz
Blastomyces dermatitidis
States bordering Mississippi and Ohio river basins up to Canada, Central America
Enters via pulmonary route -> pulmonary infection
Can lead to disseminated dz: skin, bone, granulomatous nodules
Thick refractile wall around yeast forms
Same size as RBCs
Reproduce by Broad Based Budding!
Coccidiodes immitis
Mycelial form in soil -> spherule
Dried out mycelial forms fracture into arthroconidia
-go airborne, stay in air for long periods of time
deposit in lungs
barrel shaped in air
In lung spherule fills w/ endospores
Larger than RBC
Release endospores into surrounding tissues
Southwestern US, Mexico, C. America
San Joaquin Valley Fever
Asx or mild
Severe pneumonia
Disseminated dz: CNS (meningitis), skin, bone, joints
Sporothrix schenckii
Soil and vegetation
Thorns
Sphangnum moss
Small pustule/ucer at site of initial infection
Nodules appear along draining lymphatics
Painless
Tx: itraconazole, potassium iodide (kids)
“plant a rose in a Pot(assium iodide)”
Paracoccidiodes brasiliensis
Latin America
Enters through respiratory route
Disseminates widely progressive dz
- severe pneumonia
- granulomatous changes in mucous membranes and skin
captain’s wheel appearance
