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ID 6.2


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Blastomyces dermatitidis
Dimorphic: mycelium at culture and yeast at body temperature
As yeast, budding w/BROAD BASE
Blastomyces dermatitidis
Endemic to OH/MI river valleys
Occurs in otherwise healthy people ("wrong place, wrong time")
Blastomyces dermatitidis
Spore inhalation
1/2 infections are symptomatic, presenting with acute and possibly chronic infection
Blastomyces dermatitidis
(acute infection)
Acute pneumonia
Often unrecognized
May resolve, become worse or resort to chronic infection
Blastomyces dermatitidis
(chronic infection)
Hematogenous spread, including skin ("watery ulcers" & "cold abscesses"), bone/joint, and GU (esp. male) involvement
Blastomyces dermatitidis
Identifying organism in sputum/tissue
Blastomyces dermatidis
Surgical debridement of abscesses
Itraconazole (mild forms) and possibly amphotericin B (severe infections)
2 species (immitus and posadasii)
"San Joaquin Valley Fever"
Mycelium in soil, airborn spores
Occupation hazard for people working outside
(geographic distribution)
Desert southwest
Acute Coccidoiodes Infection
Primary infection: symptomatic 40% (general URI); asymptomatic 60%
Chronic Pulmonary Coccidioidomycosis
Cavitary disease (of those w/underlying health conditions)
Outcomes for Primary Symptomatic Coccidioides Infection
Dissemination (including basilar meningitis), Chronic Pulmonary Sequelae, Progressive Pulmonary Disease
Disseminated Coccidiodes Infection
Immunocompromized hosts
Dark races
Pregnant women
Culture (spherules w/endospoores, DNA probes)and serology (IgM, then IgG)
Diagnosing disseminated Coccidioides infection?
CF antibody titer > 1:16
Itraconazole/fluconazole for mild infections
Intrathecal amphotericin B (serious infections, meningitis)
Outcome for Coccidioides-induced meningitis?
Likely incurable
Requires lifelong therapy
Cryptococcus neoformans
Found in aged pigeon droppings
Worldwide distribution
Aerosolized and inhaled
Pulmonary infection
Basilar meningitis
Skin/soft tissue/bone dissemination
Sample stains
Large polysaccharide capsule
(stains pink with mucicarmine)
India ink (thin-based bud)
Serology (latex agglutination cryptococcal polysaccharide antigen test)
Easy to culture
Histoplasma capsulatum
(geographic distribution)
Similar to blastomyces but includes Houston
Found in bat/avian excrement
Histoplasma capsulatum
Pulmonary disease
Progressive disseminated histoplasmosis (via mononuclear spread, like miliary TB)
Focal infections
Histoplasma capsulatum (pulmonary disease)
Acute pulmonary disease
Chronic cavitary pulmonary histoplasmosis (in those w/structural lung defects)
Histoplasma capsulatum
(disseminated disease)
Mouth ulcers
Addison's disease (adrenal glands)
Granulomatouos hepatitis
Histoplasma capsulatum
Depends on nature of infection!
Culture: chronic pulomonary and dissemination; serology: self-limited and chronic pulmonary; urine antigen: disseminated
Sporathrix schenckii
(geographic distribution)
Widely distributed in nature
Gross on plant material
Sporathrix schenckii
Traumatic inoculation (i.e. thorn puncture)
Skin lesion, lymphogenous spread, bone/joint involvement (strong synovial inflammation), dissemination (including meningitis) in AIDS patients
Sporathrix scheckii
Cigar-shaped organisms (difficult to isolate)
Serology: compliment fixation and agglutination tests
Paracoccidiodes brasiliensis
"South American Blastomyces"
Paracoccidioides brasiliensis
Subclinical primary pulmonary disease w/significant hilar adenopathy
Paracoccidioides brasiliensis (pulmonary disease)
Acute RARE
Chronic 50% time
Paracoccidiodes brasiliensis (disseminated disease)
Mucocutaneous lymphangitic involvement (potentially disfiguring) but RARE
Paracoccidioodes brasiliensis
Histology and serology (useful)
Paracoccidiodes brasiliensis (therapy)

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