Profils de résistance aux antibiotiques des souches de staphylococcus aureus isolées des mammites bovines

Abstract

Bovine mastitis is a highly prevalent disease in dairy cows, with the vast majority of mastitis cases being due to an intramammary bacterial infection. Staphylococcus aureus represents the main pathogen responsible for these infections. Mastitis caused by S. aureus often exhibits resistance to multiple classes of antimicrobial agents, which limits the choice of therapeutic options in the field. Our main aim is to determine the antibiotic resistance profile of S. aureus strains isolated from mastitic milk. The study involved the analysis of 30 milk samples collected from different farms in the wilaya of Mostaganem, including 25 samples from clinically healthy cows and 5 from clinical mastitis cases. Isolation of S. aureus was performed from mammalian milk, and identification was carried out using catalase and free coagulase tests, followed by susceptibility testing to determine their resistance profile against antibiotics according to the standard agar disk diffusion method. Out of the 25 analyzed samples from clinically healthy cows, 10 samples were contaminated with S. aureus and were identified. All strains isolated from clinical mastitis cases were identified as S. aureus. The antibiotic susceptibility results revealed a total resistance rate of 100% to cefoxitin and penicillin, 60% to tetracycline, and 60% to erythromycin. All isolated strains confirm the presence of the MRSA (Methicillin-Resistant Staphylococcus aureus) phenotype. Similarly, all isolated MRSA strains exhibited a multidrug-resistant (MDR) profile. This work indicates a critical incidence of methicillin-resistant Staphylococcus aureus (MRSA) in mastitic milk, and multidrug-resistant (MDR) strains were detected .