First isolation of Trichophyton fischeri in the United States.

A 49-year-old male with Pneumocystis carinii pneumonia was seen at Bellevue Hospital in New York, N.Y. Sputum samples yielded cultures of Candida lusitaniae, Mycobacterium avium, and a filamentous fungus, Trichophyton fischeri. T. fischeri is a nonpathogenic fungus which resembles the dermatophyte Trichophyton rubrum. This is the first record of the species from U.S. sources. This case exemplifies the ecological differences between T. fischeri and T. rubrum and illustrates how correct identification of the former species can minimize diagnostic confusion. The two species are distinguished from each other by the type of growth on Casamino Acids-erythritol-albumin agar and by micromorphological differences.