Azole Resistance and erg11 Gene Expression in Non-albicans Candida Strains Isolated from Raw Milk and Human Samples: Cross-sectional Study from 14 Farms and 2 Hospitals, Iran, 2021-2022

 Nowadays, non-albicans Candida are common in human pathogens, and some of these cases were found in milk. Therefore, as well as the lack of accurate estimates of its global prevalence and severity, the present study aims to assess the demographic features of non-albicans Candida (NAC) spp. and determine the species distribution of NAC. It was also evaluating the in vitro Azole susceptibility of NAC species and identified the erg11 gene and erg11 expression in fluconazole-resistant isolates of NAC spp., in Iran.

 In the present study, non-albicans Candida, including Candida glabrata, Candia krusei, Candida parapsilosis, and Candida tropicalis, were isolated and identified from 14 farms (raw milk) and human patients using culture methods, Real-Time PCR and sequencing. The resistance and susceptibility of the samples to azole were examined and erg11 expression was evaluated by RT-qPCR. The results were analyzed by REST Software to compare the levels of erg11 gene expression involved in drug resistance of NAC.

 74 and 52 NAC strains were isolated in 262 collected milk samples and human samples. Based on ITS sequencing, 0.76% were identified as C. glabrata, 2.29% C. tropicalis, 4.19% C. parapsilosis, and 19.8% C. krusei. The expression of erg11 gene in the NAC was increased in samples isolated from humans compared to samples isolated from livestock (P>0.05), while no significant difference was found in the case of Candida glabrata isolated from both sources (P<0.05). All NAC isolates were sensitive to flucytosine.

 NAC isolates from cows' milk have antifungal resistance genes while they had not taken any antifungal drugs. The resistance gene is transferred from antifungal agents in crop protection medications. Clinical isolates also had increased resistance to antifungal activity. Also, using Azole antibiotics can increase resistance gene level activity. This phenomenon should be considered for treatment program protocols.