Genotypic identification and antimicrobial susceptibility profiles of coagulase-negative staphylococci isolated from sheep’s milk

Abstract

Mastitis affect milk production and dairy products in sheep farming. Its main etiological agents are coagulase-negative staphylococci (CoNS). Identification based on DNA sequencing is considered the gold-standard method for these organisms. The present study identify CoNS species from 32 sheep’s milk isolates through polymerase chain reaction (PCR) with restriction fragment length polymorphism (RFLP) of the gap gene and to ascertain their susceptibility to nine selected antimicrobial agents by the agar disk diffusion technique. Four PCR-RFLP profiles were obtained, corresponding to three CoNS species: S. epidermidis (59.4%), S. chromogenes (34.4%), and S. devriesei (6.2%). All isolates were susceptible to cefalotin, ceftiofur, and penicillin/novobiocin. Twenty-one isolates (65.6%) were resistant to at least one antimicrobial agent, and 11 isolates (34.4%) were susceptible to all tested agents. Four isolates (12.5%) were multidrug-resistant, including an S. epidermidis isolate which exhibited resistance to oxacillin, confirmed by amplification of the mecA gene. In addition to constituting an animal health problem and causing economic losses to sheep farmers, CoNS have zoonotic potential