Molecular Characterization of Multi-Drug Resistant Fungal Isolates Obtained from Raw Cow Milk in Bowen University, Nigeria

Abstract

Cow milk is a highly nutritious food but many factors predispose it to microbial contamination. There is paucity of information on antifungal-resistant pathogens. Hence the study investigated the fungi from fresh cow milk samples and their resistance to some antifungals. Twenty-seven (27) fungi were isolated from forty-three (n=43) milk samples on PDA (Potato dextrose agar) media, re-cultured in glucose yeast extract broth, and incubated for 24 hours at 25°C. Taxonomic characterization on the isolates was done using photomicrography. Percentage occurrence of the isolates was determined. Molecular characterization was carried out on some isolates which were 100% resistant to antifungals; ketoconazole, amphotericin B, and clotrimazole using ITS1 and ITS4 primers. Isolate sequences were subjected to BLAST analysis and compared with representatives in GenBank. Kruskal-Wallis and Mann-Whitney Tests were used to analyze the data. Phylogenetic analysis and morphological characterization identified isolates as Rhodotorula paludigena, Candida sp and Candida tropicalis which had occurrence of 31.8%, 31.8% and 36.6% respectively. Level of resistance to ketoconazole (100%) and amphotericin B (92%) was significantly higher than clotrimazole (59%) (p< 0.05), while between ketoconazole and amphotericin B, there was no significant (p> 0.05) difference. Unprocessed raw milk is a potential source of drug-resistant pathogenic fungi. Pasteurization of raw milk is highly encouraged before consumption.