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Advances in Animal and Veterinary Sciences

Research Article
Adv. Anim. Vet. Sci. 6(4): 161-168
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Gamal Younis1, Asmaa Sadat*, Mona Maghawry2

1Department of Bacteriology, Mycology and Immunology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 35516; 2Animal Health Research Institute, Dokki, Egypt.

Abstract | Staphylococcus aureus (S. aureus) is one of the major pathogens involved in bovine mastitis. Monitoring of antibiotic use could assess the hazard of S. aureus in cow’s milk. The objective of this study was to determine the prevalence of S. aureus in mastitic dairy cows in some localities in Dakahlia and Damietta Governorates, Egypt and to phenotypically characterize the antimicrobial susceptibility of the obtained isolates. In that context, a total of406 milk samples were collected from dairy cows suffering from clinical (n=100) and subclinical (n=306) mastitis from four different dairy farms. Milk samples were subjected to conventional bacteriological isolation techniques, and confirmed as S.aureus by using PCR assay targeting nuc (S. aureus-specific thermonuclease) and coa (coagulase) genes. Interestingly, 28 S. aureus strains tested negative to coagulase enzyme phenotypically were positive for Cao gene. The prevalence rate of S. aureus in clinical and subclinical mastitic milk samples was 66% (66/100) and 30.72% (94/306) respectively with an overall prevalence of 39.40% (160/406). All S.aureus isolates were tested against 10 different antimicrobials belonged to 7 antimicrobial classes. S.aureus strains exhibited a high rate of resistance to vancomycin (93.75%), penicillin (86.25%), trimethoprim (60%), and oxacillin (58.75%). A medium rate of resistance was observed to clindamycin (41.25%), ciprofloxacin (41.25%) and erythromycin (37.5%).On the other hand; S.aureus isolates displayed a low frequency of resistance to gentamicin (21.25%), ampicillin/sulbactam (20%) and chloramphenicol (18.75%). The multidrug-resistance to three or more classes of antimicrobials was detected in 108isolates (67.5 %). In conclusion, antimicrobial resistance of S.aureus was prevalent in dairy herds in the study area which represents a public health hazard. Hence, control and prevention policies should be implemented to minimize the dissemination of resistance trend.

Keywords | Antimicrobial resistance, Cows, Coa gene, Mastitis, Nuc gene, Staphylococcus aureus.