FA - Micro - Mycology Flashcards
Treatment for systemic mycosis?
- Fluconazole (local infection)
- Itraconazole (local infection)
- Amphotericin B (systemic infection)
3 features about systemic mycoses?
- ALL can cause pneumonia
- Can disseminate
- ALL caused by dimorphic fungi: cold (20C)=mold, heat(37C)=yeast.
Only exception: Coccidioidomycosis - spherule (not yeast) in tissue.
Systemic mycosis can mimic what?
TB (granuloma formation), EXCEPT, unlike TB, have no person-person transmission.
Histoplasmosis - Endemic location?
Mississippi and Ohio river valleys.
Histoplasmosis cause?
Pneumonia.
Histoplasmosis special feature?
Macrophage filled with Histoplasma (smaller than RBC) - Histo Hides (within macros).
BIRDS (eg starlings) and BATS droppings.
Blastomycosis - Endemic location?
States east of Mississippi River and Central America.
Blastomycosis - cause?
Inflammatory lung disease - can disseminate to skin and bone.
Forms granulomatous nodules.
Blastomycosis - Special feature?
Broad-base budding (same as RBC).
Coccidioidomycosis - Endemic location?
Southwestern US, California.
Coccidioidomycosis - cause?
- Pneumonia
- Meningitis
- Can disseminate to bone and skin.
Coccidioidomycosis - Special features?
- Case rate UP after earthquakes (spores in dust are thrown up in the air and become spherules in the lungs).
- Spherule (MUCH LARGER than a RBC) filled with endospores.
Paracoccidioidomycosis - Endemic location?
Latin America.
Paracoccidioidomycosis - Special feature?
Budding yeast with “captain’s wheel” formation (MUCH LARGER THAN RBC).
Tinea versicolor - Cause?
Malassezia spp. (Pityrosporum spp.) ==> A yeast-like fungus (NOT A DERMATOPHYTE despite being called tinea).
Tinea versicolor - Pathogenesis?
Degradation of lipids produces acids that damage MELANOCYTES –> hypopigmented and/or PINK patches.
Tinea versicolor - When?
Can occur ANY TIME of year, but more common IN SUMMER ==> Hot, humid weather.
Tinea versicolor - treatment?
- Topical miconazole
2. Selenium sulfide (Selsun)
Tinea versicolor - Microscopic morphology?
“Spaghetti and meatball” appearance.
Other tineae?
Tinea pedis Tinea cruris (groin) Tinea corporis Tinea capitis Tinea unguium (onychomycosis, on fingernails)
Other tineae - Features?
Pruritic lesions with central clearing resembling a RING.
Other tineae - causes?
By dermatophytes - Microsporum, Trichophyton, Epidermophyton.
Dermatophytes - Microscopic morphology?
BRANCHING SEPTATE HYPHAE visible on KOH preparation with BLUE FUNGAL STAIN.
C.albicans - causes?
- Oral-esophageal thrush in immunocompromised (Neonates+ Steroids + Diabetics + AIDS).
- Vulvovaginitis (diabetes, use of antibiotics).
- Diaper rash
- Endocarditis in IVDA
- Disseminated candidiasis (any organ)
- Chronic mucocutaneous candidiasis
C.albicans - Treatment?
Vaginal –> Topical azole.
Oral/esophageal –> Nystatin, fluconazole, or caspofungin.
Systemic –> Fluconazole, ampho B, caspofungin.
C.albicans - dimorphic?
YES:
- Pseudohyphae and budding yeasts at 20C.
- Germ tubes at 37C.
Aspergillus fumigatus - causes?
- Invasive aspergillosis
- Allergic bronchopulmonary aspergillosis (ABPA)
- Aspergillomas in lung cavities (especially after TB)
- Some produce aflatoxins –> HCC.
Invasive aspergillosis - features?
- In immunocompromised
2. In Chronic granulomatous disease
Allergic bronchopulmonary aspergillosis - features?
- Asthma - CF associations.
2. May cause bronchiectasis/eosinophilia.
A.fimugatus - Dimorphic?
NO - Septate hyphae that branch at 45 degree angle ==> Produces conidia in radiating chains at END of CONIDIOPHORE.
C.neoformans - causes?
- Cryptococcal meningitis.
2. Cryptococcal encephalitis (“soap bubble” lesions in brain), primarily in IMMUNOCOMPROMISED.
C.neoformans - Morphology + Capsule?
Heavily encapsulated yeast.
5-10μm with NARROW BUDDING.
C.neoformans - Dimorphic?
NO!!!
C.neoformans - where?
In soil, PIGEON droppings.
C.neoformans - transmission?
Inhalation with hematogenous dissemination to meninges.
C.neoformans - Culture?
Sabouraud agar.
C.neoformans - Stain?
- India ink ==> Clear halo.
2. Mucicarmine ==> Red INNER CAPSULE.
C.neoformans - diagnostic test?
Latex agglutination test detects polysaccharide capsular antigen and is more specific.
Mucormycosis - target group?
- Ketoacidotic diabetics.
2. NEUTROPENIC patients (Eg leukemia).
Mucormycosis - Pathogenesis?
Fungi proliferate in blood vessel WALLS when there is excess ketone and glucose ==> Penetrate cribriform plate ==> Enter brain.
Mucormycosis - Features?
- Rhinocerebral, frontal lobe abscesses.
- Headache
- Facial pain
- Black necrotic eschar on face.
- May have cranial nerve involvement.
- CAVERNOUS SINUS THROMBOSIS.
Mucormycosis - Treatment?
Surgical debridement + Amphotericin B.
Mucor - Microscopy?
Irregular, broad, nonseptate hyphae branching at wide angles.
P.jirocevii?
Pneumocystis pneumonia - Diffuse interstitial pneumonia.
P.jirovecii - transmission?
Inhaled.
P.jirovecii - CXR/CT appearance?
Diffuse, BILATERAL ground-glass opacities on CXR/CT.
P.jirovecii - Diagnosis?
Lung biopsy or lavage.
P.jirovecii - microscopy?
Disc-shaped yeast forms on METHENAMINE SILVER stain of lung tissue.
P.jirovecii - treatment?
- TMP-SMX
- Pentamidine
- Dapsone (proph only)
- Atovaquone (proph only)
P.jirovecii - prophylaxis in AIDS patients?
Start when CD4 count drops <200cells/mm^3 in HIV patients.
Sporothrix schenckii - Causes?
Sporotrichosis.
Sporothrix schenckii - Morphology?
Dimorphic - CIGAR-SHAPED budding yeast that grows in branching hyphae with rosettes of CONIDIA.
==> Lives on vegetation.
Sporothrix schenckii - pathogenesis?
Spores are traumatically intoduced into the skin, typically by a thron (rose gardener’s disease) –> Local pustule or ulcer with nodules along draining lymphatics –> Ascending lymphangitis.
Little systemic illness.
==> DISSEMINATED DISEASE possible in IMMUNOCOMPROMISED host.
Sporotrichosis - treatment?
Itraconazole or potassium iodide.
“(San Joaquin)” Valley fever:
CODDIDIOIDOMYCOSIS.
Tinea capitis:
Head + Scalp:
- Associated with LYMPHADENOPATHY.
- Alopecia.
- Scaling.
Tinea corporis:
Torso:
==> Erythematous scaling rings (“ringworm”) + Central clearing.
Tinea corporis can be acquired from contact with …?
An infected CAT or DOG.
Tinea cruris - Occurs in …?
INGUINAL AREA.
Tinea cruris - Often does NOT show …?
The CENTRAL clearing seen in tinea corporis.
Tinea pedis - 3 varieties:
- Interdigital (MC).
- Moccasin distribution.
- Vesicular type.
P.jirovecii - Originally classified as …?
PROTOZOAN. Now, yeast-like FUNGUS.