Evaluation of the isolation rate of Staphylococcus aureus bacteria from milk of cows infected with various types of mastitis in Khuzestan province and investigation of the prevalence of the mecA gene and methicillin resistance in isolates
Subject Areas : Veterinary Clinical PathologyHamzeh Asadi 1 , Daryoush Gharibi 2 , Meisam Makki 3
1 - Ph.D. Graduate in Veterinary Bacteriology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
2 - Associate Professor, Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
3 - Assistant Professor, Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Keywords: Bovine mastitis, Khuzestan, mecA gene, Methicillin resistance, Staphylococcus aureus. ,
Abstract :
Staphylococcus aureus is one of the main causes of infectious mastitis in dairy cows, and the emergence of methicillin resistance in these bacterial strains is a major concern in veterinary medicine and public health. The aim of the present study was to evaluate the frequency of Staphylococcus aureus in the milk of cows with clinical and non-clinical mastitis in Khuzestan province and to investigate the prevalence of the mecA gene and methicillin resistance in them. In 300 milk samples from cows suspected of mastitis in Khuzestan Province, only 31 isolates (10.33%) were confirmed as Staphylococcus aureus bacteria based on diagnostic microbiology principles and final confirmation by the polymerase chain reaction molecular method based on the presence of a specific thermonuclease (nuc) gene in their genome. In a phenotypic study using the disk diffusion method and evaluation of methicillin resistance in isolates by molecular detection of the presence of the mecA gene, it was also determined that only 2 isolates (45.6%) had the aforementioned gene, while in the phenotypic method, the aforementioned isolates were not identified as methicillin-resistant Staphylococcus aureus (MRSA). Also, the study of the antibiotic resistance pattern of isolates based on the disk diffusion method and using antibiotic disks of penicillin, clindamycin, doxycycline, cefoxitin and trimethoprim-sulfamethoxazole showed that the highest resistance was related to the antibiotics trimethoprim-sulfamethoxazole and doxycycline (45.6%) and the lowest resistance was related to the antibiotic penicillin (0%). The results of this study showed that in Khuzestan Province, mastitis caused by Staphylococcus aureus bacteria, as one of the important causes of contagious mastitis, should be considered in the dairy cattle breeding management system.
