Alert on imported fungal infection: the first report of tinea capitis due to Microsporum audouinii in China

We report cases of Microsporum audouinii infections on the scalp of three individuals from an African family, originating from Mali and residing in Guangzhou. This is the first time that M. audouinii has been reported in China. The index case involved a 2-year-old boy who presented with scalp patches and scaling for more than 1 year. Dermatological examination revealed scattered dark brown patches with scales on the scalp without noticeable alopecia or pustules. Fungal microscopy revealed the presence of Ectothrix hyphae and abundant clusters of arthroconidia. On Sabouraud Dextrose Agar, pale yellow cottony colonies with radial growth appeared within 4 days. Small colonies grown on the 1% yeast extract medium exhibited pyriform and clavate microconidia, septate, thick-walled macroconidia, and comb-like hyphae. rDNA ITS Molecular identification, Matrix-assisted laser desorption ionization time-of-flight mass spectrometry and whole-genome sequencing all confirmed the presence of M. audouinii. The patient's father and second-eldest brother, both asymptomatic carriers, had positive fungal cultures for scalp dandruff, which were also identified as M. audouinii. After failing a 6-week course of oral itraconazole at 0.05 g/day with poor adherence, the patient was switched to intermittent oral terbinafine (0.08 g/day for 18 weeks) which resulted in minimal arthroconidia presence on the scalp and negative fungal culture. The father and second-eldest brother were each administered oral terbinafine at 0.25 and 0.125 g/day for 4 weeks, respectively, with negative fungal cultures post-treatment. Given the epidemiological characteristics of M. audouinii, vigilance is warranted for potential imported infections and risk of outbreaks in China.