Antimicrobial resistance and virulence profiles of Enterococcus spp. isolated from raw milk of different animal species in Türkiye

Background Milk derived from various animal species is widely consumed, necessitating careful evaluation of its microbiological safety. Enterococci are recognised as important reservoirs of antimicrobial resistance (AMR) and virulence determinants, representing a potential concern within the One Health framework. Aims This study was conducted to assess the prevalence, antimicrobial susceptibility profiles, virulence factors and resistance genes of Enterococcus spp. isolated from milk samples ( n = 250) collected from several animal species (cows, sheep, goats and water buffalo) in Türkiye. Methods Isolation was performed using selective Enterococcus agar with and without vancomycin. Identification relied on conventional microbiological techniques and polymerase chain reaction (PCR). Antimicrobial susceptibility testing was conducted using disc diffusion, while vancomycin susceptibility was evaluated using the E ‐test. Species identification, along with detection of resistance genes (glycopeptide, macrolide, tetracycline, aminoglycoside) and virulence genes, was carried out by PCR. Results A total of 250 milk samples, 151 (60.4%) Enterococcus spp. strains were recovered, with the isolated species E. faecium ( n = 59), E. faecalis ( n = 44) and others ( n = 48). Vancomycin resistance was detected in 6.6% of the isolates. The resistance rates observed in the isolates were as follows: kanamycin (79.5%), penicillin (40.4%), rifampicin (37.7%), tetracycline (11.3%), quinupristin‐dalfopristin (6%), erythromycin (5.3%) and linezolid (2.6%). Upon examination of virulence genes, Enterococcus isolates ( n = 11) were positive for gelE , eight for esp , four for asa1 and one for hlyA . The cylA gene was absent in all isolates. While resistance to tetracycline was shown to be primarily associated with tetM, erythromycin‐resistant strains were found to be positive for the mefA/E gene. Scientific Implications This study provides comparative data on species‐level differences in the occurrence and AMR patterns of Enterococcus spp. isolated from raw milk, based on phenotypic testing and selected gene detection across ruminant sources.