Mycology/Parasitology Flashcards
Histoplasmosis
-Dimorphic fungi (cold - mold, heat-yeast)
- Dimorphic
- Mississippi, Ohio river valley (bat/bird droppings, chicken coops)
- Path: Macrophage filled w oval yeast form of Histoplasma
- -> Pneumonia, HILAR lymphadenopathy
- as it targets histiocytes and the RES, may see Hepatosplenomegaly.
- pts w underlying lung ds: may develop “TB-like” sxs: weight loss, cavitations in lung, painful oral ulcers, hepatosplenomegaly.
- Disseminated only in Immunocompromised.
Histo Hides in macrophages
Dimorphic fungi
- Cold 25C: mold/hyphae. Heat/tissue: Yeast (except Cocci* spherules filled w endospores)
- -> Pneumonia and can disseminate
- Sysetmic mycoses can mimic TB (granuloma formation) but no person-person transmisstion
- Rx local infxn: Fluconazole, itraconazole
- Rx systemic infxn: Amphotericin B
- Histo, Blasto, Cocci, Paracocci, Sporo
Blastomycosis
-East of Mississippi river and Central america, Great Lakes region
-soil –> inflammatory lung ds/pneumonia –> skin and bone
-Forms granulomatous nodules*
-Biopsy: large round yeast w single broad-based bud
-Broad Based Budding (Blasto Buds Broadly)
(can all occur in immunocompetent host)
Coccidiomycosis
- Dimorphic* (spherules in tissue vs yeast)
- SW US (dust)
- ->pneumonia, meningitis* –> Skin and bone
- case rate incr after earthquakes (San Joaquin Valley - “Valley fever”)
- Path: Spherules filled w endoscpores (is a spherule in tissue (37 degree), not a yeast)
- but would see mold still at 25C
Paracoccidioidmycosis
- Dimorphic*
- Latin America
- ->chronic mucocutaneous or cutaneous ulcers –> LN –> lungs
- Cold/25C: multiple Blastoconidia
- Biopsy/heat: Budding yeast w “captains wheel” formation/budding blastoconidia
Paracoccidio parasails w the Captains Wheel all the way to Latin America
Malassezia Furfur
- -> Tinea Versicolor
- Degradation of lipids –> acids –> damage melanocytes (HYPO or HYPERpigmented patches - noticeable w tanning*)
- Hot and humid weather
- KOH prep: “spaghetti and meatball” = mold and yeast simultaneously
Common dermatophytes
Microsporum Trichophyton Epidermophyton -KOH prep: MOLD (not dimorphic) --> Tinea pedis (athlete's foot) --> Tinea cruris (Jock itch) --> Tinea corporis (ringworm, on the body) --> Tinea capitis (head, scalp) --> tinea unguium (onychomycosis on fingernails)
Candida Albicans
*Opportunistic
- Systemic or superficial YEAST infxn
- Cold: pseudohyphage, budding yeast. Warm: GERM TUBE, true hyphae
- Immunocompetent: vulvovaginitis, diaper rash
- Immunocompromised: Oral/esophageal thrush, endocarditis in IV drug users –> disseminated, chronic mucocuntaenous candidiasis
- common contaminant of sputum cultures (bc it lives in your GI/mouth/skin/vagina)
- Rx: topical azole for vagina
- Rx local: Fluconazole or Caspofungin
- Rx systemic: Amphotericin B, Fluconazole, Caspofungin
Aspergillus
*Opportunistic
- monomorphic, only exists in mold form
- 1) Invasive, esp in immunocompromised and those w CGD (i.e. Neutropenic pts/Leukemic). Lung* (hemoptysis, lung granulomas)
- 2) Allergic bronchopulmonary aspergillosis (ABPA): asthma, CF
- 3) Colonizing –> Aspergillomas
- Some produce aflataxons –> HCC
- Path: Septate hyphae w (A)cute (A)ngles. Replicate: Conidiophore
Cryptococcus neoformans
* opportunistic
- -> MENINGITIS in AIDS pts
- Found in soil, PIGEON droppings
- Inhalation –> hematogenous spread to Meninges (may cause lung issue but usually asxs)
- Latex agglutination test: polysaccharide capsule antigen
- Path: Capsular halos. “Soap bubble” lesions in the brain
- Cryptococcal pneumonia dx: red on mucicarmine stain of lung tissue/bronchoalveolar lavage.
- Urease+
Mucor spp
Rhizopus spp
*opportunistic (in DKA, leukemic, burn)
- -> Mucormycosis: DKA, Leukemic*, burn pts
- Fungi proliferate in blood vessel –> penetrate cribiform plate –> brain
- Sxs: HA, periorbital/facial pain, black necrotic eschar on face (may see CN involvement)
- Path: See broad NONSEPTATE hyphae w WIDE Angles
Pneumocystis jirovecii
*opportunistic
- “PCP”: diffuse interstitial pneumonia-a yeast, inhaled
- Path: Disch shaped yeast forms on silver stain
- Prophylax in AIDS CD4 <200
- Rx: TMP-SMX, Pentamidine, Dapsone
Sporothrix schenckii
- Dimorphic
- -> Sporotrichosis (Rose thrix/thorn! –> pustule/ulcer w nodules along lymphatics (ascending lymphangitis)
- Rx: Itraconazole or POTassium iodide (“Plant a ROSE in the POT”)
- Path: round or cigar-shaped budding yeast; granuloma formation w giant cells, surrounded by plasma cells
Giardia lamblia
protozoa - cysts in water
- Campers w FATTY-Diarrhea - why it smells so bad!
- Dx: Trophozoites (smiley face ghost thing) or Cysts (oval) in the stool
- Rx: Metronidazole
- As few as 1 organism can cause an infxn
Entamoeba histolytica
protozoa - cysts in water
- -> Amebiasis: Bloody diarrhea, Liver abscess w “anchovy paste”** exudate
- submucosal abscess ruptures in colon? see flask-shaped ulcer
- Get from cysts in water
- Dx: Trophozoites (rbc in cytoplasm**) or cysts (multi-nucleated) in stool
- Rx: Metronidazole; Iodiquinol for asxs
- as few as 1 organism can cause an infxn
Cryptosporidium
protozoa - cysts in water
- -> watery diarrhea (me), or severe diarrhea (AIDS)
- see Cysts on ACID-FAST STAIN
- Rx: Nitazoxanide in immunocompetent/me
Toxoplasma gondii
protozoa - CNS
- From cysts in meat or Cat feces
- -> Brain abscess in HIV (ring-enhancing on MRI)
- -> Congenital (crosses placenta), triad = Chorioretinitis, hydrocephalus, intracranial calcifications
- Rx: Sulfadiazine + Pyrimethamine
Naegleria fowleri
protozoa - CNS
- from swimming in freshwater lakes (“Nalgene filled w freshwater”)
- get to your brain by cribiform plate
- -> (rapid, fatal) Meningoencephalitis
- Dx: Amoebas in CSF
- Rx: Amphotericin (most die)
Trypanosoma brucei
T. gambiense
T. rhodesiense
(protozoa-CNS)
- “African sleeping sickness” from painful TseTse fly bite
- ->enlarged LN, recurring fever (due to antigenic variation), somnolence, coma
- Dx: by blood smear
- Rx: Suramin for blood borne, Melarsoprol for CNS penetration
Plasmodium
P. vivax/ovale
(protozoa - Heme infxn)
MALARIA - fever, HA, anemia, splenomegaly
- Anopheles mosquito
- fevers every 48 hr cycle
- Dormant form (hypnozoite) in liver (“VIVAx” for life = dormant form)
- Dx: blood smear, trophozoite ring form, RBC schizont w merozoites
- Rx: Chloroquine/Mefloquine, Primaquine** (test for G6PD first)
Plasmodium
P. falciparum
(protozoa - blood infxn)
MALARIA - fever, HA, anemia, splenomegaly
- Anopheles mosquito
- can be FATAL
- irregular fever patterns, parasitized rbcs occlude capillaries in brain (cerebral malaria), kidneys, lungs
- Rx: artemether/lumifantrine or atovaquone/proguanil, IV Quinidine* (if life-threatening - test for G6PD)
Plasmodium
P. malariae
(protozoa - blood infxn)
MALARIA - fever, HA, anemia, splenomegaly
- Anopheles mosquito
- 72 hour cycle of fevers (quartan*)
- Rx: chloroquine/Mefloquine, IV Quinidine* (if life-threatening - test for G6PD)