Subtyping options of Microsporum canis strains using microsatellite and multilocus typing

Microsporum canis is one of the most common dermatophyte causing infections in animals and humans worldwide. However, molecular epidemiological studies on this dermatophyte are still rare because of lack of variable DNA sequences and polymorphic markers. In order to investigate variable DNA sequence and microsatellite markers, M. canis strains (n=65) isolated from humans, animals with and without lesions were selected and subtyped by multilocus sequence typing (MLST) and multilocus microsatellite typing (MLMT). Firstly, we used a limited set of strains for screening variability among 12 housekeeping genes and among microsatellite loci. No intraspecific variability was detected in 10 out of 12 housekeeping genes, and only ITS and IGS regions showed two and three sequence genotypes, respectively. Microsporum canis, M. audoinii and M. ferrugineum were discriminated by six housekeeping genes. Overall, eighteen microsatellite genotypes (A-R) were recognized using multilocus microsatellite typing (MLMT) based on 8 loci, allowing a subdivision of the strains into two populations following of Bayesian statistical approach. Genotype C was isolated from dogs, cats, humans, whereas other genotypes were host specific. Data suggest that molecular characterization of ITS and IGS regions is useful to detect limited genetic variability within M. canis isolates, but not MLST. Nonetheless, microsatellite-analysis is a powerful tool for subtyping and can be used for surveillance studies and for gaining insight into the epidemiology of infections due to M. canis.