Microsporum canis is a zoophilic dermatophyte—the most common fungus isolated from dogs and cats, globally. To invade the skin, this pathogen uses different enzymes which may be associated with virulence, that contribute to the fungal pathogenicity.

A new study published in Micropathologia compared the expression of enzymes that may be associated with the virulence and thermotolerance of M. canis strains isolated from dogs, cats and humans.

Here, the in vitro expression of enzymes keratinase, catalase, urease, hemolysin and aspartic protease were evaluated in 52 M. canis strains—recently isolated from 14 human patients, 12 dogs, 15 symptomatic and 11 asymptomatic cats. In addition, the thermotolerance was assessed by comparative analysis of fungal growth at 25°C and 35°C.

The results revealed that keratinase activity was low in 34 and moderate in 18 strains. Aspartic-protease activity was low in 7; moderate in 33; and high in 12 strains. While hemolysin activity was low in 44 and moderate in 8 strains. All strains were classified as low producers of catalase. All but three strains produced urease in vitro, with a broad range of activity. The strains presented in vitro growth at the two studied temperatures – were classified as presenting low (36.5%), medium (44.3%) or high (19.2%) thermotolerance. On the other hand, there was no statistical significant difference in the new putative virulence-associated factors studied among the different hosts—which suggested that they may have a similar role on human, cat and dog infection. Meanwhile, no difference was observed between strains isolated from symptomatic and asymptomatic cats.

The findings indicated that these factors have a limited impact on the fate of feline dermatophytosis caused by M. canis.

Source: Micropathologia. 2020 Jul 8. doi: 10.1007/s11046-020-00470-9.