Microsporum canis strains from animals with or without skin lesions and humans with Tinea corporis: a variable virulence and antifungal profile

The enzymatic and antifungal profiles of dermatophytes might play an important role in causing infections in humans and animals but these data on Microsporum canis is seldom reported. This study evaluates the ability of M. canis strains in producing virulence factors, its in vitro antifungal profile and the relationship between virulence, antifungal profile and occurrence of lesions in animals and humans. A total of 100 M. canis strains from humans with tinea corporis (n. 10) and from animals with (n . 64) and without skin lesions (n 26) was employed to evaluate phospholipase (Pz), hemolytic (Hz), lipase (Lz), catalase (Ca) activities and thermotolerance (GI%). Additionally, in vitro antifungal profile was evaluated using the CLSI broth microdilution method. A statistically significant difference (p < 0.05) in the Lz and Ca values were registered among M. canis strains from hosts with and without lesions. Voriconazole (VOR), terbinafine (TER) and posaconazole (PSZ) were the most active drug against M. canis strains, followed by ketoconazole (KTZ) griseofulvin (GRI), itraconazole (ITZ) and fluconazole (FLZ) in rank activity order. In animals with skin lesions an higher hemolytic activity and a lower catalase activity was observed in low azole susceptible strains than that observed in high susceptible ones. M. canis strains with higher thermotholerance showed low susceptibility to the antifungals drugs than those with lower thermotollerance. The significant positive correlation with azole susceptibility of M. canis and virulence factors (i.e., hemolysin and catalase activities) suggests that both the enzyme patterns and antifungal susceptibility might play a pivotal role in the appearance of skin lesions in animals and humans.