Coagulase‐Negative Staphylococci Collected from Bovine Milk: Species and Antimicrobial Gene Diversity

Abstract

Abstract The aim of this study was to examine the genetically mediated antimicrobial resistance in 94 coagulase‐negative staphylococcal ( CNS ) milk isolates (buffalo, n = 88, and cow, n = 6), and to determine whether antimicrobial resistance profiles differed between bacterial species. Our analysis of 94 CNS isolates from milk confirmed the well‐established multiresistant character of staphylococci in the dairy setting. Resistance against oxacillin, ciprofloxacin and cefoxitin was most frequently observed. Eleven CNS species isolated from buffalo's and cow's milk samples were 100% sensitive to gentamicin, erythromycin, clindamycin and ciprofloxacin. Resistance to oxacillin was attributed to the mecA gene in 44.7% of the oxacillin‐resistant isolates. The mecA gene was detected in S taphylococcus intermedius , epidermidis , hominis , hyicus , caprae , sciuri , lugdunensis and xylosus while totally absent in chromogenes , simulans and lentus . Of the 11 CNS species, S . epidermidis , S . lugdunensis , S . hominis , S . xylosus and S . intermedius were the only species that exhibited multiple resistance. Practical Applications Studying coagulase‐negative staphylococci ( CNS ) at the species level can provide valuable information about species‐specific differences that can be vital data to prevent the dissemination of antimicrobial‐resistant genes and resistant pathogens to the community. CNS have long been regarded as pathogenic, but their important role as colonizers of the bovine udder has been recognized and studied in recent years. CNS have become increasingly resistant to multiple antibiotics. In recent years, increasing numbers of reports have shown that the mecA gene is present in CNS strains, including hospital‐acquired infections, community‐associated methicillin‐resistant S taphylococcus aureus infections, animal epidermis, beaches and public transportation systems. Therefore, it is highly important to detect the mecA gene as a marker to investigate antibiotic resistance in milk that may represent a serious health and economic concern.