Fungi in Immunocompromised Flashcards
A patient with ____ is at extremely high risk for invasive fungal infection.
graft-versus-host disease
The most medically important yeast are?
candida and cryptococcus
The most medically important molds are?
zygomycetes, aspergillus, fusarium
This fungus is difficult to classify, but medically important.
pneumocystis jiroveci (PCP)
The most medically important dimorphic fungi are?
histoplasma capsulatum, coccidiodes immitis, blastomyces dermatitidis
cryptococcus neoformans
encapsulated, round yeast obtained by inhaling yeast from soil contaminated with bird-droppings
what is the key virulence factor for cryptococcus neoformans?
capsule (can cause fungal meningitis in AIDS patients)
diagnosis of cryptococcus neoformans
antigen detection test is 90% sensitive, can test for antigen in CSF and serum
how do we prevent cryptococcal neoformans in AIDS patients?
prophylactic fluconazole
aspergillus fumigatus
spores ubiquitous in the soil, suppressed immune system cannot clear like a normal person, looks like brush under microscope
pathogenesis of aspergillus
inhaled spores turn into septate hyphae which invade the lung tissue and cause blood vessel damage, death
Why is aspergillus a double-edged sword?
invasive in immunosuppressed, causes allergic sinusitis and bronchospasms in immune hyperactive
zygomycoses
broad aseptate hyphae, often rhinocerebral in patients with DM, disseminated in immunocompromised
what groups are at risk for zygomycosis?
patients with diabetes mellitis (due to acidosis b/c grows better in acidic conditions), burn patients, immunocompromised
fusarium
septate, often confused with aspergillus, lots of clinical resistance, invasive disease starts in sinus because large conidia get trapped
what is the characteristic shape of fusarium conidia?
banana-shaped
how to diagnose fusarium
blood cultures, only mold that can be reliably recovered this way
how to diagnose pnuemocystis jiroveci
direct examination of sputum only (no PRC, no culture)
pathogenesis of pneumo jiroveci
slowly “drown” from proteinaceous material in alveoli
Rx for pneumocystis
prophylaxis, TMP-SMX
Immunocompetent hosts with dimorphic fungi suffer from?
no symptoms, or self-limiting mild flu-like respiratory illness
coccidiodes immitis usually causes?
flu-like illness in immunocompetent, pneumonia in immunocompromised
Coccidiodes mold phase called ______ and pathogenic phase called _____.
arthrospores, spherules (yeast-like)
Histoplasma capsulatum
infection occurs from inhaling microconidia from soil enriched with bird/bat feces
who is at greatest risk for histoplasma?
Ohio River Valley, lower Mississippi, Caribbean basin, spelunkers
histoplasma may be confused with what other disease?
tuberculosis, due to granulomas on chest radiograph, pulmonary disease manifestation
how to diagnose histoplasma
bronchoscopy, blood cultures, detection in urine or BAL, yeast are lemon shaped
blastomyces can be diagnosed fairly reliably by?
observation of yeast with broad-based budding
conditions commonly associated with blastomyces infection
skin lesions, flu-like illness, pulmonary infection, bone and joint lesions, GU tract infections in males
