Microsporum canis is a zoophilic dermatophyte and the most common fungus isolated from dogs and cats worldwide. To invade skin, this pathogen uses different enzymes, which may be associated with virulence, that contribute to the fungal pathogenicity. The aim of this study is to compare the expression of enzymes that may be associated with virulence, and thermotolerance of M. canis strains isolated from dogs, cats, and humans. The in vitro expression of the enzymes keratinase, catalase, urease, hemolysin, and aspartic protease was evaluated in 52 M. canis strains recently isolated from 14 human patients, 12 dogs, 15 symptomatic, and 11 asymptomatic cats. In addition, thermotolerance was assessed by comparative analysis of fungal growth at 25 °C and 35 °C. 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. 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. There was no statistically significant difference in the new putative virulence-associated factors studied among the different hosts, which suggests that they may have a similar role on human, cat, and dog infection. Also, no difference was observed between strains isolated from symptomatic and asymptomatic cats. This suggests that these factors have a limited impact on the fate of feline dermatophytosis caused by M. canis.

犬小孢子菌是一种嗜动物性皮肤癣菌，是世界范围内从狗和猫身上分离出来的最常见的真菌。为了侵入皮肤，这种病原体使用不同的酶，这些酶可能与毒力有关，有助于真菌的致病性。本研究的目的是比较可能与从狗、猫和人类分离的犬支原体菌株的毒力和耐热性相关的酶的表达。在 52 M 中评估角蛋白酶、过氧化氢酶、脲酶、溶血素和天冬氨酸蛋白酶的体外表达。犬最近从 14 名人类患者、12 只狗、15 只有症状和 11 只无症状猫中分离出菌株。此外，通过对 25 °C 和 35 °C 下真菌生长的比较分析来评估耐热性。角蛋白酶活性在 34 株中较低，在 18 株中中等。天冬氨酸蛋白酶活性在 7 个菌株中较低，在 33 个菌株中中等，在 12 个菌株中较高。44 株溶血素活性低，8 株中等。所有菌株都被归类为过氧化氢酶的低生产者。除了三种菌株外，所有菌株都在体外产生脲酶，具有广泛的活性。在两个研究温度下体外生长的菌株被分类为呈现低 (36.5%)、中 (44.3%) 或高 (19.2%) 耐热性。在不同宿主之间研究的新的假定毒力相关因素没有统计学上的显着差异，这表明它们可能对人类、猫和狗的感染具有相似的作用。此外，从有症状的猫和无症状的猫中分离出的菌株之间没有观察到差异。这表明这些因素对猫皮肤癣菌病的命运影响有限。M.犬。