Antifungal Drug-resistant Isolates from Animal Mycoses

Abstract

Animal mycoses caused by antifungal drug-resistant strains can readily be transmitted from animals to humans as a zoonosis. We report the first isolation of a terbinafine (TRBF) -resistant Microsporum canis strain from a feline dermatophytosis in Beijing. The strain exhibited TRBF minimum inhibitory concentration (MIC) of >16 μg/mL but remained susceptible to itraconazole (ITCZ)(MIC 0.023 μg/mL). We investigated the expression of the pleiotropic drug resistance (PDR1) and multidrug resistance (MDR1, MDR2, and MDR4) genes in the TRBF-resistant and TRBF-susceptible strains of Microsporum canis by Real-Time quantitative PCR (RT-qPCR) analysis. The expression of PDR1, MDR1, MDR2, and MDR4 genes was 2 to 4 times higher in the TRBF-resistant strain than in the TRBF-susceptible strains. We also isolated an azole-resistant strain of Malassezia pachydermatis from a canine Malasseziosis. The isolate exhibited an MIC of 320 μg/ml for ITCZ by broth microdilution (BM) assay, >32 μg/ml for ITCZ by E-test, and >32 μg/ml for KTCZ by E-test. We sequenced the ERG11 gene from this isolate and detected missense mutations (A412G and C905T) in the ERG11 open reading frame (ORF).