A New Medium that Promotes In Vitro Mass Sporulation of Microsporum canis

Microsporum canis is one of the most common zoophilic pathogenic fungi, and infections are typically managed using empirical antifungal therapy. The increasing incidence of M. canis infections has led to a growing demand for antifungal susceptibility assays in clinical settings, particularly in pediatric department, to guide drug selection and to monitor therapeutic responses in highly inflammatory cases. However, susceptibility testing methods rely heavily on sporulation capacity of M. canis, and more than half of the clinical isolates fail to produce sufficient microconidia in commonly-used media for reliable testing.In this study, we evaluated a novel a rice bran medium (RBM) for its ability to enhance microconidia production in clinical isolates of M. canis. RBM demonstrated a significantly greater sporulation-inducing effect than conventional media, including potato dextrose agar (PDA), Sabouraud dextrose agar (SDA), and oatmeal agar (OA), which are commonly used in clinical laboratories. Sporulation efficiency varied with RBM concentrations, with 4% RBM showing the highest efficacy. Under this concentration, abundant microconidia were consistently produced by testing clinical strains after 7-10 days of incubation at 30 ℃ across. These findings suggest that RBM represents a practical and effective alternative medium for promoting sporulation and facilitating antifungal susceptibility in clinical settings.