Dimorphic fungi

Background

Microbiology

• Broad category of fungi that exist in a mold form at lower temperatures in the environment, and a yeast form at higher temperatures in the host body
• Cryptococcus does exhibit dimorphism, though it is predominately yeast and its dimorphism is not likely related to disease
• Often referred to as endemic fungi based on their geographic niches

Organism	Distribution	Diseases	Treatment
Blastomyces species	eastern US and Canada, with some reported in Africa	pulmonary infection, verrucous skin lesions, osteomyelitis, CNS infection	itraconazole (with amphotericin B induction if severe)
Coccidioides species	southwestern US and parts of South and Central America	pulmonary infection, verrucous skin lesions, osteomyelitis, CNS infection	fluconazole (with amphotericin B and flucytosine induction if severe)
Histoplasma capsulatum	worldwide, including eastern North America, Central and South America, sub-Saharan Africa, and parts of Southeast Asia	pulmonary infection, CNS infection	itraconazole (with amphotericin B induction if severe)
Paracoccidioides brasiliensis	South America	pulmonary infection	itraconazole (with amphotericin B induction if severe)
Sporothrix schenckii	essentially worldwide	nodular lymphangitis	itraconazole
Talaromyces marneffei	Southeast Asia	disseminated (common in advanced HIV), pulmonary infection, abdominal abscess, skin lesions, osteomyelitis	amphotericin B induction followed by itraconazole

• Blastomyces species, including Blastomyces dermatitidis complex (Blastomyces dermatitidis and Blastomyces gilchristii), helices, silverae, parvus
• Histoplasmosis capsulatum (var. capsulatum and var. duboisii)
• Coccidiodes species, including Coccidioides immitis and Coccidioides posadasii
• Paracoccidioides species, including Paracoccidioides brasiliensis and Paracoccidioides lutzii
• Talaromyces marneffei
• Emergomyces species, including Emergomyces pasteurianus, Emergomyces africanus, Emergomyces orientalis, Emergomyces canadensis, Emergomyces europaeus
• Sporothrix species complex (Sporothrix brasiliensis, Sporothrix schenckii, Sporothrix globose, Sporothrix luriei)

Epidemiology

• Endemic dimorphic fungi are widely distributed1

Histoplasmosis

Histoplasmosis

Coccidiomycosis

Coccidiomycosis

Blastomycosis

Blastomycosis

Prevention

Laboratory Safety

• Many are risk group 3 and need to notify lab if suspected
• Opening the plates outside of a BSC is one of the highest risk actions