Mycology and Parasitology Flashcards
Systemic mycoses characteristics
All can cause pneumonia and disseminate
- Dimorphic fungi: cold = mold (20C); heat = yeast (37C) –> except coccidioidomycosis is spherule not yeast
- Tx:
- Local infection - fluconazole/itraconazole
- Systemic - amphotericin B
**Systemic can mimic TB, but no person-to-person transmission!
Types of systemic mycoses
- Histoplasmosis
- Blastomycosis
- Coccidioidomycosis
- Paracoccidioidomycosis
Histoplasmosis
Mississippi + Ohio River valleys –> pneumonia
- Bird/bat droppings
- Macrophage filled with histoplasma (smaller than RBC)
- Histo Hides (in macrophages)*
Blastomycosis
Mississippi River/Central America
- Inflamm lung disease, can disseminated to Bone/skin
- Makes granulomatous nodules
- Broad-based budding (same size as RBC)
- Blasto Buds Broadly*
Coccidioidomycosis
Southwest US/California
- Pneumonia/meningitis, can disseminate to bone/skin
- Incr rate after earthquake bc spores in dust –> into air –> spherules in lung
- Spherules (much larger than RBC) filled w/ endospores
- (San Joaquin) Valley fever*
- Desert bumps = erythema nodosum*
- Desert rheumatism = arthralgias*
Paracoccidioidomycosis
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
Cutaneous mycoses = tinea
Tinea versicolor
Other: Tinea pedis (foot), tinea cruris (groin), tinea corporis (ringworm), tinea capitis (head, scalp), tinea unguium (onychomycosis, fingernails)
*KOH prep - see mold hyphae
Tinea versicolor
Malassezia furfur
- Degradation of lipids makes acids –> damage melanocytes –> hypo/hyperpigmented patches
- Hot, humid weather
- Dx - “spaghetti and meatball” appearance
- Tx - topical miconazole, selenium sulfide (Selsun)
Leslie got rid of her furfur fungus w/ head + shoulders = selenium sulfide
Opportunistic fungal infections
1) Candida albicans
2) Aspergillus fumigatus
3) Cryptococus neoformas
4) Mucor and Rhizopus app.
5) Pneumocystic jirovecci
6) Sporothrix schenckii
Candida albicans
- Systemic or superficial fungal infection
- Oral/esoph thrush - immunocompromised
- Vulvovaginitis - diabetes/abx use
- Diaper rash
- Endocarditis in IV drug users
- Disseminated candidiasis
- Tx:
- Oral/esoph = fluconazole/caspofungin
- Vaginal = topical azole
- Systemic = fluconazole/caspofungin/amphotericin B
*alba = white (white pseudohyphae and budding yeasts) –> dimorphic (buds/yeast)
Aspergillus fumigatus
- Invasive aspergillosis - immunocompromised and CGD
- Allergic bronchopulmonary aspergillosis (ABPA) - asthma/CF –> bronchiectasis/eosinophilia
- Aspergillomas - in lung cavities, esp after TB
- HCC - some aspergillus make aflotoxin, assoc w/ HCC
- Incr IgE eosinophilia
- Septate hyphae that branch at 45degr (acute) angle [NOT DIMORPHIC]
Cryptococcus neoformans
Cryptococcal meningitis, cryptococcosis
- Soil/pigeon droppings –> inhale, then disseminates hematog to meninges
- Sabouraud agar, India ink stain. Encapsulated yeast (halos), NOT DIMORPHIC
- Latex agglutination test - detects polysaccharide capsule
Mucor and Rhizopus spp
Mucormycosis –> in DKA, leukemic pts
- Fungi in blood vessel walls when excess ketones/glucose –> penetrates cribiform plate –> enters brain
- Rhinocerebral/frontal lobe abscesses
- HA, face pain, black necrotic face eschar, CN involvement
Tx = amphotericin B
Pneumocystis jirovecci
Pneumocystis pneumonia (PCP) = diffuse interstitial pneumonia
- Yeast inhaled –> most asxs
- Immunocompromised - predisporse
- CXR - diffuse, bilateral
- Dx - lung biopsy/lavage
Tx = TMP-SMX, pentamide Ppx = dapsone, atovaquone; when CD4<200
*Disc shaped yeast on silver stain
Sporothrix schenckii
Sporotrichosis
- Spores enter traumatically through skin (thorn prick) –> pustule/ulcer with nodules along lymphatics
- Little systemic illness
Tx = itraconazole/POTassium iodide
*Dimorphic, cigar shaped budding yeast, lives on vegetation
“Plat a ROSE in the POT”
Types of parasites
- Protozoa
- Nematode (roundworms)
- Cestodes (tapeworms)
- Trematodes (flukes)
Protozoa
GI infections - giardia, entamoeba histolytica, cryptosporidium
CNS infections - toxoplasma, naegleria fowleri, trypanosoma brucei
Heme infections - plasmodium, babesia
Visceral - trypanosoma cruzi, leishmania donovani
STDs - trichomonas vaginalis
GI infections from protozoa
- Giardia
- Entamoeba
- Histolytica
- Cryptosporidium
Gut Entered High Cut
Giardia lamblia
Giardiasis - bloating, flatulence, foul-smelling + fatty diarrhea
- Transmission cysts in water (campers/hikers)
- Dx - trophozoites or cysts in stool
- Tx - metronidazole
fat-rich Ghiradelli –> fatty stools
Entamoeba histolytica
Amebiasis - bloody diarrhea (dysentery), liver abscess (“anchovy paste” exudate)
- Sx - RUQ pain (flask-shaped ulcer if colon submucosal ulcer ruptures)
- Transmission - cysts in water
- Dx - trophozoites (w/ RBC in cytoplasm) or cysts in tool
- Tx - metronidazole; iodoquinol if asx cyst passers