Fungi & Parasites Flashcards
1
Q
what are the 2 bugs that cause “Valley Fever?”
A
- Coccidioides immitis
- C. posadasii
2
Q
which coccidioides bug is more common and what geographical area is it in?
A
- C. immitis
- SW US –> San Joaquin Valley
3
Q
how do you get C. immitis? what is the yeast form called? mode of infection?
A
- inhale from the soil
- yeast form = spherule = BUZZ
- spherule contains endospores; it ruptures and the endospores go and form new spherules
4
Q
what is weird about the C. immitis spherules?
A
- the spherules don’t actually infect the cells; they cause pain because they are pushing around the lung tissue
5
Q
C. immitis clinical ds
A
- 60-65% of infections are asymptomatic
- mainly a pulmonary infection if it is symptomatic
- can disseminate in immunocompromised pts
6
Q
what labs can dx C. immitis?
A
- KOH prep = dissolves cells EXCEPT fungal cells
- grows on Sabouraud dextrose agar in 3-4d
- serology and CXR
7
Q
tx for c. immitis?
A
- DOC = ketoconazole; alternative = fluconazole
- for prego pt = amphotericin B b/c -azoles are teratogenic
- for IC pts use amphotericin B followed by 1 year of fluconazole; use lifelong fluconazole if there is a CNS infection
8
Q
Blastomyces dermatitidis: appearance of mold vs. yeast forms
A
- mold = hyphae w/ nondescript conidia
- yeast = broad-based budding yeast = BUZZ
9
Q
geography for Blastomyces? associated with?
A
- found in Ohio and Mississippi river valleys and Great Lakes
- assoc w/ decaying matter (soil and leaf litter), rotting wood (beaver dams)
10
Q
Blastomyces dermatitidis clinical manifestations
A
- 50% = flu-like or asymptomatic
- pneumonia in severe ds = acute onset, lobar infiltrates, high fever, cough
- can disseminate to skin and bones rarely
- can go to CNS in AIDS pts
11
Q
dx and tx for Blastomyces dermatitidis
A
- dx = microscopy followed by culture; serology can be done but not helpful
- tx = amphotericin B for severe ds; can use itraconazole in immune competent adults
12
Q
Histoplasma capsulatum: mold v. yeast appearance
A
- mold = hyphae w/ microconidia and tuberculate macroconidia
- yeast = intracellular, infects WBC
13
Q
epidemiology for histoplasma?
A
- Ohio, Missouri, and Mississippi river basins
- found in bird and bat droppings
- risk factors = bird roosts, spelunking, building demolition = BUZZ
14
Q
histoplasma clinical ds?
A
- pulmonary sx will vary based on inhaled inoculum
- low intensity = 90% are asx
- high intensity can be acute or progressive; acute = flu-like, cough, chest pain and CXR = patchy infiltrates; progressive = IC pts = destruction and fibrosis of pulmonary tissue
15
Q
histoplasma dx and tx
A
- dx: microscopy of stained smears = intracellular yeast in WBC (macrophage); ELISA of plasma; culture on Sabouraud dextrose agar but only + in 30-60% of pts
- tx: for severe acute ds = IV amphotericin B followed by 12 weeks itraconazole; mild pulmonary ds = intraconazole
16
Q
how do you get Paracoccidioidomycosis? where? buzz word? treatment?
A
- inhaled from the soil
- found in central and S. America
- BUZZ = “pilot’s wheel” = multiple budding yeast
- tx = itraconazole
17
Q
most common species of Aspergillosis?
A
- A. flavus
18
Q
possible ways to get Aspergillosis?
A
- conidia are inhaled
- get it from air, soil, decaying matter
- can be inhaled nosocomially from shower heads, water tanks, plants
19
Q
what are the 3 categories of ds possible in Aspergillosis?
A
- allergic
- noninvasive
- invasive
20
Q
what are the 3 types of allergic Aspergillosis?
A
- IgE-mediated asthma (type 1 HS)
- allergic bronchopulmonary aspergillosis (ABPA)
- extrinsic allergic alveolitis AKA farmer’s lung
21
Q
IgE-mediated asthma
A
- type 1 HS rxn
- allergic rxn to inhaled spores
- sx = asthma, pulm infiltrates, eosinophilia, elevated serum IgE
- hypersensitivity to Aspergillus antigens (skin test)
22
Q
ABPA: allergic bronchopulmonary aspergillosis
A
- growth in bronchial tree secretion
- HS pneumonitis (Types I, III, and IV)
- occurs in pts w/ asthma or CF; rarely happens in absence of clinical asthma
23
Q
Farmer’s lung
A
- type of HS pneumonitis (type III HS)
- immunologic response to an inhaled agent
- exposure to moldy hay or contaminated compost
- acute damage caused by cytokines
- sx resolve when you remove the irritant
24
Q
what are some other types of hypersensitivity pneumonitis? common thread to these case scenarios?
A
- winemaker’s lung = Botrytis cinerea
- coffee worker’s lung = coffee bean dust
- poultry worker’s lung = Avian antigens
- lab worker’s lung = rodent antigens
- common thread = the symptoms come back when you get re-exposed; improve when stimulus removed
25
fungal ball - aspergilloma
- noninvasive pulmonary ds
- spherical mass of intertwined septate hyphae
- usually underlying ds = CF, TB or chronic bronchitis
- tx not warranted unless massive hemoptysis present --> surgical excision
26
aspergillosis - invasive pulmonary ds
- systemic infection; rapidly fatal unless dx early and tx aggressively
- IC host = neutropenia and corticosteroid therapy are major risk factors --> AIDS, bone marrow transplants, leukemia, lymphoma
- clinically = fever, pulm infiltrates, chest pain, hemoptysis; mortality >70%
27
how can you dx Aspergillosis?
- microscopy/culture of sputum: acute angled branching hyphae = BUZZ
- CXR for fungal ball
- immunoassays for invasive aspergillosis
28
tx and prevention for Aspergillosis
- allergic aspergillosis tx = oral corticosteroids; oral itraconazole for recurrent or chronic ABPA
- aspergilloma tx = surgical resection; could use oral itraconazole
- invasive aspergillosis tx = voriconazole
- prevention = antigen avoidance and air filtration
29
what is the difference in appearance b/w mucor and aspergillus?
- aspergillus = 45 degree branching hyphae (acute angle = aspergillus)
- mucor = 90 degree branching hyphae
30
what populations are most susceptible to mucormycosis (zygomycosis)?
- mainly worried about ketoacidotic diabetics
- could also be pts w/ leukemia, lymphoma, solid transplant pts, extensive burns
- specifically marrow transplant pts on voriconazole
31
what do you see happen w/ ketoacidotic diabetics that get mucor?
- rhinocerebral zygomycosis
| - gross black pus draining out of nose and eyes
32
how do you dx and tx mucor?
- dx = KOH prep and culture; see NONseptate hyphae w/ 90 degree branching
- tx = tx underlying IC state; systemic amphotericin B; may need surgical debridement
33
what is stachybotrys chartarum? what disease does it cause?
- mold that grows on wet wood and paper
| - no specific disease but associated w/ hemoptysis and asthma-like sx
34
what is the #1 cause of atypical pneumonia in AIDS pts?
- Pneumocystis jiroveci
35
what is the pathogenesis of P. jiroveci?
- binds to receptors on alveolar macrophages
- induces diffuse alveolar damage
- leakage of exudate
36
is there anything done to prevent AIDS pts from getting P. jiroveci pneumonia?
- AIDS pts usually put on Bactrim to prevent P. jiroveci once their CD count <200
37
how do you dx and tx P. jiroveci pneumonia?
- dx = Giemsa stain for trophic forms (DENTED HELMETS); Gomori methenamine silver stain for cyst wall
- tx = TMP-SMX (Bactrim) is DOC; alternatives = pentamidine, dapsone
38
Paragonimus westermani is know as ??
- lung fluke
| - is a species of trematode
39
what do you get P. westermani from? where is it found? shape of adult fluke?
- larvae eaten in undercooked crab, crayfish --> snail = intermediate host
- found in Asia, Africa, India, Latin America --> look for hx of travel
- adult fluke looks like coffee bean shape
40
what signs & sx would you see w/ P. westermani?
- pt travels and comes back and gets TB-like sx
- start coughing up eggs in sputum
- "coffee ground" or "rusty colored" sputum
- assoc w/ bad sushi; usually hx of travel to Japan
41
dx and tx for P. westermani?
- dx = microscopy of sputum and feces; golden brown operculated eggs; CXR = patchy, cloudy infiltrate
- tx = praziquantel is DOC; alternative = triclabendazole
