Fungi in Immunocompromised

Question 2

A patient with ____ is at extremely high risk for invasive fungal infection.

Answer 2

graft-versus-host disease

Question 3

The most medically important yeast are?

Answer 3

candida and cryptococcus

Question 4

The most medically important molds are?

Answer 4

zygomycetes, aspergillus, fusarium

Question 5

This fungus is difficult to classify, but medically important.

Answer 5

pneumocystis jiroveci (PCP)

Question 6

The most medically important dimorphic fungi are?

Answer 6

histoplasma capsulatum, coccidiodes immitis, blastomyces dermatitidis

Question 7

cryptococcus neoformans

Answer 7

encapsulated, round yeast obtained by inhaling yeast from soil contaminated with bird-droppings

Question 8

what is the key virulence factor for cryptococcus neoformans?

Answer 8

capsule (can cause fungal meningitis in AIDS patients)

Question 9

diagnosis of cryptococcus neoformans

Answer 9

antigen detection test is 90% sensitive, can test for antigen in CSF and serum

Question 10

how do we prevent cryptococcal neoformans in AIDS patients?

Answer 10

prophylactic fluconazole

Question 11

aspergillus fumigatus

Answer 11

spores ubiquitous in the soil, suppressed immune system cannot clear like a normal person, looks like brush under microscope

Question 12

pathogenesis of aspergillus

Answer 12

inhaled spores turn into septate hyphae which invade the lung tissue and cause blood vessel damage, death

Question 13

Why is aspergillus a double-edged sword?

Answer 13

invasive in immunosuppressed, causes allergic sinusitis and bronchospasms in immune hyperactive

Question 14

zygomycoses

Answer 14

broad aseptate hyphae, often rhinocerebral in patients with DM, disseminated in immunocompromised

Question 15

what groups are at risk for zygomycosis?

Answer 15

patients with diabetes mellitis (due to acidosis b/c grows better in acidic conditions), burn patients, immunocompromised

Question 16

fusarium

Answer 16

septate, often confused with aspergillus, lots of clinical resistance, invasive disease starts in sinus because large conidia get trapped

Question 17

what is the characteristic shape of fusarium conidia?

Answer 17

banana-shaped

Question 18

how to diagnose fusarium

Answer 18

blood cultures, only mold that can be reliably recovered this way

Question 19

how to diagnose pnuemocystis jiroveci

Answer 19

direct examination of sputum only (no PRC, no culture)

Question 20

pathogenesis of pneumo jiroveci

Answer 20

slowly “drown” from proteinaceous material in alveoli

Question 21

Rx for pneumocystis

Answer 21

prophylaxis, TMP-SMX

Question 22

Immunocompetent hosts with dimorphic fungi suffer from?

Answer 22

no symptoms, or self-limiting mild flu-like respiratory illness

Question 23

coccidiodes immitis usually causes?

Answer 23

flu-like illness in immunocompetent, pneumonia in immunocompromised

Question 24

Coccidiodes mold phase called ______ and pathogenic phase called _____.

Answer 24

arthrospores, spherules (yeast-like)

Question 25

Histoplasma capsulatum

Answer 25

infection occurs from inhaling microconidia from soil enriched with bird/bat feces

Question 26

who is at greatest risk for histoplasma?

Answer 26

Ohio River Valley, lower Mississippi, Caribbean basin, spelunkers

Question 27

histoplasma may be confused with what other disease?

Answer 27

tuberculosis, due to granulomas on chest radiograph, pulmonary disease manifestation

Question 28

how to diagnose histoplasma

Answer 28

bronchoscopy, blood cultures, detection in urine or BAL, yeast are lemon shaped

Question 29

blastomyces can be diagnosed fairly reliably by?

Answer 29

observation of yeast with broad-based budding

Question 30

conditions commonly associated with blastomyces infection

Answer 30

skin lesions, flu-like illness, pulmonary infection, bone and joint lesions, GU tract infections in males