EMERGENCE OF EXTENDED SPECTRUM Β-LACTAMASE (ESBL) PRODUCING AND COLISTIN-RESISTANT ENTEROBACTERIACEAE IN MILK AND SOME DAIRY PRODUCTS: MICROBIAL SAFETY AND QUALITY ASSESSMENT

Abstract

Milk and dairy products are crucial component of the Egyptian daily diet. A major concern in the 21^st century is the contamination of dairy products with microorganisms that convey antimicrobial-resistant genes (ARGs), particularly extended spectrum β-lactamases (ESBLs) and colistin genes. Therefore, this study investigated the total viable count, coliforms, Enterobacteriaceae, total Staphylococci, and aerobic spore formers in 90 samples of raw milk, Baladi yoghurt, and white soft cheese (30 of each). Coupled with the phenotypic and genotypic characterization of the ESBL-producing and colistin resistant Enterobacteriaceae strains. The incidences of aerobic spore formers, Staphylococci, and Enterobacteriaceae were 100, 100, 83% ;100, 67, 100% and 100, 63, 33% in milk, Baladi yoghurt, and white soft cheese, respectively. The phenotypic screening of the identified Enterobacteriaceae isolates (n=136) revealed that 80.8% (n=110) were ESBL-producing, while merely 2.9% were colistin resistant. Genotypic analysis revealed that bla_CTX-M and bla_SHV were presented in 99% of the identified isolates, although bla_TEM was only present in 84.5% of them. Interestingly, the bla_OXA gene was not detected. Notably, all phenotypically colistin resistant isolates harboured mcr-1 gene. Those findings indicated that milk and dairy products can help in spreading of beta-lactam resistant bacteria, emphasizing the importance of further research to mitigate them in the dairy sector.