AGENT OF YEAST
The escalating incidence of yeast and yeastlike fungi isolated from environmental specimens has emphasized the importance of identifying yeast isolates to the species level. With greater immunosuppression, the variety of organisms implicated in disease also expands. Isolation of other yeasts from environmentall samples is also increasing. Infections caused by many yeasts are extremely aggressive and difficult to treat. Yeast fungi can be classified into one of two groups, yeasts and yeastlike fungi. Isolates that reproduce sexually, either by forming ascospores or basidiospores, are truly yeasts. Most isolates that are not capable of sexual reproduction or whose sexual state has not yet been discovered are correctly termed yeastlike fungi.
Torula spp. is isolated from soil and is normal human flora in the oral cavity, urogenital area, and gastrointestinal tract. It is an opportunistic pathogen, usually eliciting disease in debilitated patients. The lungs and kidneys are primarily affected, although, the fungus can disseminate through the blood to the rest of the blood, causing gungemia and septic shock. A case of congenital transfer has been reported.
In laboratory, samples may show budding yeast cells.
Yeast isolates producing the enzyme urease can be detected easily with Christensen urea agar. The slants are inoculated and incubated at room temperature for 48 hours.
Almost all clinically encountered Torula organisms are urease-positive.