MICROBIOLOGY MYCOLOGY Flashcards
Systemic mycosis
can cause pneumonia and can disseminate. All are caused by dimorphic fungi: cold (20°C) = mold; heat (37°C) = yeast. The only exception is coccidioidomycosis, which is a spherule (not yeast) in tissue. Treatment: fluconazole or itraconazole for local infection; amphotericin B for systemic infection. Systemic mycoses can mimic TB (granuloma formation), except, unlike TB, have no person-person transmission.
Histoplasmosis
blastomycosis
coccidiodomycosis
paracoccidiodomycosis
Histoplasmosis
Histoplasmosis
Mississippi and Ohio River valleys. Causes pneumonia. Macrophage filled with Histoplasma (smaller than RBC) Histo hides (within macrophages). Bird or bat droppings.
Blastomycosis
States east of 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)
Blasto buds broadly
Coccidiodomycosis
Southwestern United States, California. Causes pneumonia and meningitis; can disseminate to bone and skin. Case rate after earthquakes (spores in dust are thrown up in the air and become spherules in lungs).
Spherule (much larger than RBC) filled with endospores
Coccidio crowds. “(San Joaquin) Valley fever” “Desert bumps” = erythema nodosum “Desert rheumatism” = arthralgias
Paracoccidiodomycosis
Latin America.
Budding yeast with “captain’s wheel” formation (much larger than RBC)
Paracoccidio parasails with the captain’s wheel all the way to Latin America
Tinea versicolor
Caused by Malassezia furfur. Degradation of lipids produces acids that damage melanocytes and cause hypopigmented and/or hyperpigmented patches. Occurs in hot, humid weather.
Treatment: topical miconazole, selenium sulfide (Selsun). “Spaghetti and meatball” appearance
Other tineae
Includes tinea pedis (foot), tinea cruris (groin), tinea corporis (ringworm, on body), tinea capitis (head, scalp), tinea unguium (onychomycosis, on fingernails).
Pruritic lesions with central clearing resembling a ring, caused by dermatophytes (Microsporum, Trichophyton, and Epidermophyton). See mold hyphae in KOH prep, not dimorphic.
