An atypical Microsporum canis isolate.

An atypical strain of Microsporum canis isolated from a two-year-old boy with tinea corporis is described. When cultured on Lactritmel agar the strain presented the typical pigment of M. canis without developing characteristic macroconidia. After 6 weeks, scarce, rudimentary, fusiform macroconidia 120-150 microns long developed on Lactritmel and Sablac microcultures. In vitro, the strain developed hair perforating organs. Experimental inoculation of a healthy volunteer produced a tinea with typical fluorescence and endoectothrix attack. After isolation the strain remained stable. These results differ from the results reported by English and Tucker. This is the first atypical strain of M. canis reported in Venezuela.