Mastitis is one of the most frequent and costly production diseases of dairy cattle. It is frequently treated with broad-spectrum antimicrobials. The objectives of this work were to investigate the prevalence of Staphylococcus aureus and Escherichia coli , find out the antimicrobials used in mastitis treatment, and explore the antimicrobial resistance profile including detection of resistance genes. Bacterial species and antimicrobial resistance genes were confirmed by the polymerase-chain reaction. A total of 450 cows were screened, where 23 (5.11%) and 173 (38.44%) were affected with clinical and sub-clinical mastitis, respectively. The prevalence of S. aureus was 39.13% (n = 9) and 47.97%(n = 83) while, E. coli was 30.43% (n = 7) and 15.60% (n = 27) in clinical and sub-clinical mastitis affected cows, respectively. The highest antimicrobials used for mastitis treatment were ciprofloxacin (83.34%), amoxycillin (80%) and ceftriaxone (76.67%). More than, 70% of S. aureus showed resistance against ampicillin, oxacillin, and tetracycline and more than 60% of E. coli exhibited resistance against oxacillin and sulfamethoxazole-trimethoprim. Selected antimicrobial resistance genes ( mec A, tet K, tet L, tet M, tet A, tet B, tet C, sul 1, sul 2 and sul 3) were identified from S. aureus and E. coli . Surprisingly, 7 (7.61%) S. aureus carried the mec A gene and were confirmed as methicillin-resistant S. aureus (MRSA). The most prevalent resistance genes were tet K 18 (19.57%) and tet L 13 (14.13%) for S. aureus , whereas sul 1 16 (47.06%), tet A 12 (35.29%), sul 2 11 (32.35%) and tet B 7 (20.59%) were the most common resistance genes in E. coli . Indiscriminate use of antimicrobials and the presence of multidrug-resistant bacteria suggest a potential threat to public health.

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