Microbiology Mycology - First Aid Flashcards
Systemic mycoses can all cause…
pneumonia and can disseminate.
All systemic mycoses 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 for Systemic Mycoses
Local infection: Fluconazole or Itracoazole
Systemic infection: Amphotericin B
Systemic mycoses can mimic…
TB (w/ granuloma formation) but unlike TB, they have no person-to-person transmission.
Systemic mycoses types (4)
- Histoplasmosis
- Blastomycosis
- Coccidioidomycosis
- Paracoccidioidomycosis
Histoplamosis features (4)
- Mississippi and Ohio River valleys
- causes pneumonia
- macrophages filled with histo
- bird or bat droppings
Blastomycosis features (4)
- states east of Mississippi river (and Central America)
- causes inflammatory lung disease and can disseminate to bone and skin
- forms granulomatous nodules
- broad-base budding
Coccidioidomycosis features (6)
- Southwest US
- causes pneumonia and meningitis
- can disseminate to skin and bone
- spherule filled with endospores
- erythema nodosum (desert bumps)
- arthralgias (desert rheumatism)
Coccidioidomycosis rates increase after…
earthquakes which causes spores in the dust to be thrown up into the air.
Paracoccidioidomycosis features (2)
- Latin America
- budding yeast w/ “captain’s wheel” formation
Tinea versicolor is caused by…
Malassezia furfur which degrades lipids producing acids that damage melanocytes and cause hypopigmented/hyperpigmented patches.
Tinea versicolor occurs in…
hot, humid weather.
Has a “spaghetti and meatball” appearance.
Treatment for tinea versicolor
topical miconazole, selenium sulfide
Other tineae (cutaneous mycoses) include…
tinea pedis (foot) tinea cruris (groin) tinea corporis (ringworm, on body) tinea capitis (head, scalp) tinea unguium (onychomycosis on nails)
Dermatophytes include (3):
- Microsporum
- Trichophyton
- Epidermophyton
Dermatophytes cause..
pruritic lesions with central clearing resembling a ring.
In a KOH prep, dermatophytes show as…
mold hyphae, not dimorphic.
Opportunistic fungal infections (6)
- Candida albicans
- Aspergillus fumigatus
- Cryptococus neoformans
- Mucor and Rhizopus
- Pneumocystis jirovecii
- Sporothrix schenckii
Candida albicans causes:
- oral and esophageal thrush
- vulvovaginitis
- diaper rash
- endocarditis in IV drug users
- mucocutaneous candidiasis
Treatment for Candida albicans
Vaginal - topical azole
Oral/esophageal - fluconzaole, caspofungin
Systemic - fluconazole, Amphotericin B, Caspofungin
Aspergillus fumigatus casues…
Allergic Bronchopulmonary Aspergillosis: associated with asthma and CF; may cause bronchiectasis and eosinophilia
Aspergillomas in lung cavities, esp after TB.
Some species of Aspergillus produce…
aflatoxins which are associated with hepatocellualr carcinoma.
Candida albicans features (3)
- dimorphic yeast
- pseudohyphae and budding yeasts at 20 C
- germ tubes at 37 C
Aspergillus fumigatus features (4)
- invasive esp in those with chronic granulomatous disease
- septate hyphae that branch at acute (45 degree) angles
- conidiophore with radiating chains of spores
- not dimorphic
Cryptococcus neoformans causes…
cryptococcal meningitis (soap bubble lesions in the brain) and cryptococcosis.
Cryptococcus neoformans features
- heavily encapsulated yeast
- not dimorphic
- soil, pigeon droppings
- wide capsular halos and unequal budding
Cryptococcuus neoformans is acquired through…
inhalation with hematogenous dissemination to the meninges.
The most specific test for cryptococcus neoformans is…
latex agglutination test which detects polysaccharide capsular antigen.
Mucor and Rhizopus cause…
mucormycosis mostly in ketoacidotic diabetic and leukemic pts.
Mucor and Rhizopus fungi proliferate in…
blood vessel walls when there is excess ketone and glucose, penetrate the cribiform plate and enter the brain. This causes rhinocerebral, frontal lobe abcesses.
Signs of Mucor and Rhizopus infection
- HA
- facial pain
- black necrotic eschar on face
- cranial nerve involvement
Treatment for Mucor and Rhizpus
Amphotericin B
Mucor appearance
irregular, broad, nonseptate hyphae branching at wide angles
Pneumocystis jirovecii causes…
pneumocystis pneumonia, a diffuse interstitial pneumonia.
Pneumocystis jirovecii features
- inhaled
- usually asymptomatic
- disc-shaped yeast forms on methenamine silver stain of lung tissue
Treatment/prophylaxis for pneumocystis jirovecii
TMP-SMX, pentamidine, dapsone (prophylaxis only), atovaquone (prophylaxis only)
Start prophylaxis for pneumocystits when…
CD4 count drops to less than 200 in HIV pts.
Sporothrix schenckii causes…
sporotrichosis. When spores are traumatically introduced into the skin, typically by a thorn (rose gardener’s disease), it causes a pustule/ulcer with nodules along draining lymphatics.
Sporothrix schenckii features (3)
- dimorphic
- cigar-shaped budding yeast
- lives on vegetation
Treatment for Sporothrix schenckii
Itraconazole or Potassium iodide
