S9.4e Molecular epidemiology of Microsporum canis infection in Japan

Abstract S9.4 Free oral presentations (late breaking), September 23, 2022, 4:45 PM - 6:15 PM Objectives From a series of epidemiological surveys by the Japanese Society for Medical Mycology, it is estimated that the number of Microsporum canis (M. canis) infections in Japan has increased in recent years. The purpose of this study was to observe this trend by multilocus microsatellite (MLMT) analysis, a sensitive molecular marker. Methods DNA was extracted from 103 strains of M. canis isolated between 2017 and 2022 from Japanese patients and pet animals. Using the DNA, PCR targeting six individual microsatellites was performed. The size of each of these amplicons was measured by capillary electrophoresis, and their genotypes were determined from the combinations of their sizes. Results A total of 27 genotypes were detected among the 103 strains. Among the 27, 15 had been reported in studies of strains isolated before 2017, whereas 12 were newly determined in the present study. The genotype most frequently detected in the present study was genotype A, being present in 28 of the 103 strains. By geographical region, genotype A was found in strains distributed over a wide area of Japan. Genotype A strains have been isolated from cats purchased at pet shops and/or owners of these pet animals. The highest incidence of genotype in a study of strains isolated in 2010-2014 was also genotype A. Therefore, a large number of M. canis infections originating from pet shops and animal breeders are likely prevalent in Japan today. Furthermore, a relatively large number of strains were identified as genotypes rare or absent in 2010-2014. Conclusions The increase in the number of M. canis infections in recent years may be the increase in infections of different genotypes, in addition to the base of constant infections by genotype A, by the present MLMT analysis.