[Survey of keratinophilic fungi from soils and mating behaviour of Microsporum canis from human ringworm cases in Hokkaido Prefecture in Japan].

From 383 (38.3%) of a total 1000 of soil samples, collected from Hokkaido prefecture, keratinophilic fungi have been isolated using hair baiting technique. The fungi isolated were as follows: 318 strains of Trichophyton ajelloi (including 90 strains of Arthroderma uncinatum), 59 of Microsporum cookei (including 13 of Nannizzia cajetani), 32 of Chrysosporium keratinophilum, 23 of C. tropicum, 15 of Chrysosporium anamorph of A. tuberculatum, 6 of T. terrestre (including 3 of A. insingulare and one of A. quadrifidum), 4 of Chrysosporium sp., 2 of M. canis (including one of N. otae), one of M. gypseum, and one of Ctenomyces serratus. This is the first isolation of N. otae from soil. Because of the successful isolation of N. otae (and its anamorph) from soil sample, (+) strain of M. canis was suggested to be popular in Hokkaido prefecture. The prevalence of (+) strain of M. canis was investigated using 279 isolates obtained from human ringworm cases. Among the 279 isolates, 257 were (-) mating type, 8 were (+) and 14 were nonreactive. Results of the present study indicate that the distribution of keratinophilic fungi from soils in Hokkaido prefecture is markedly different from that in the southern parts of Japan. The unexpected isolation of N. otae and its anamorph from soil samples as well as the significant population of N. otae(+) strain from human ringworms suggest the peculiar distribution pattern of N. otae (+) in Hokkaido prefecture.