Comparative Genomic Analysis and Antimicrobial Resistance Profile of Enterococcus Strains Isolated from Raw Sheep...

The role of Enterococcus spp. in food is debated since this group of lactic acid bacteria contains opportunistic pathogenic strains, some of which exhibit a multidrug-resistant profile. In livestock farms, the use of antibiotics is the most common practice to deal with mastitis-causing bacteria. However, the heavy usage and/or misuse of antibiotics has led to the emergence of antibiotic resistance. This study aimed to genetically and phenotypically characterize Enterococcus strains isolated from raw sheep milk. Samples were collected over one year from the bulk tank of a dairy sheep farm and cultured on selective media. Isolates were purified and analyzed by whole-genome sequencing and antimicrobial susceptibility testing. The isolates were divided into clusters and the corresponding species were identified along with their genes related to virulence and antibiotic resistance. The pan-, core- and accessory-genomes of the strains were determined. Finally, the antibiotic-resistant profile of selected strains was examined and associated with their genomic characterization. These findings contribute to a better understanding of Enterococci epidemiology, providing comprehensive profiles of their virulence and resistance genes. The presence of antibiotic-resistant bacteria in raw sheep milk destined for the production of cheese should raise awareness.