Epidemiological investigation of non-albicans Candida species recovered from mycotic mastitis of cows in Yinchuan, Ningxia of China

BACKGROUND: Candida spp. is the vital pathogen involved in mycotic mastitis of cows. However the epidemiology and infection of Candida species in mycotic mastitis of cow in Ningxia province of China has not been explored. In the present study, the epidemiology, antimicrobial susceptibility and virulence-related genes of non-albicans Candida (NAC) species were investigated. METHODS: A total of 482 milk samples from cows with clinical mastitis in four herds of Yinchuan, Ningxia were collected and used for the isolation and identification of mastic pathogens by phenotypic and molecular characteristics, and matrix-assisted laser desorption ionization-time of flight mass spectrometry. The antimicrobial susceptibility to antifungal agents was also determined by a disk diffusion assay. The presence of virulence-related genes was determined by polymerase chain reaction (PCR). RESULTS: A total of 60 isolates from nine different Candida species were identified from 256 (60/256, 23.44%) milk samples. The most frequently identified species in cows with clinical mastitis groups were Candida krusei (n = 14) and Candida parapsilosis (n = 6). Others include Candida lipolytica, Candida lusitaniae, Cryptococcus neoformans. But no Candida albicans was identified in this study. Interestingly, All C. krusei isolates (14/14) were resistant to fluconazole, fluorocytosine, itraconazole and ketoconazole, 2 out of 14 C. krusei were resistant to amphotericin, and 8 out of the 14 were resistant to nystatin. Similarly, all six C. parapsilosis isolates were resistant to fluorocytosine, but susceptible to fluconazole, ketoconazole and nystatin; two of the six were resistant amphotericin and itraconazole. Molecularly, all of the C. parapsilosis isolates carried eight virulence-related genes, FKS1, FKS2, FKS3, SAP1, SAP2, CDR1, ERG11 and MDR1. All of the C. krusei isolates contained three virulence-related genes, ERG11, ABC2 and FKS1. CONCLUSION: These data suggested that Candida species other than C. albicans played a pathogenic role in mycotic mastitis of cows in Yinchuan, Ningxia of China. The high incidence of drug-resistant genes in C. parapsilosis and C. krusei also highlighted a great concern in public and animal health in this region.