In the present study, 750 buffaloes from six buffalo farms were screened for subclinical mastitis and positive samples were screened for antimicrobial susceptibility test. A total of 310 positive subclinical mastitis with prevalence of 41.33 % were subjected to E. coli isolation. Out of 310 milk samples 94 E. coli strains were isolated with prevalence of 30.32%. All the 94 E. coli strains were studied for their antimicrobial resistance pattern against 10 beta lactam antibiotics. The study indicated that greater percentages of isolates were resistant to Cefotaxime (53.19%), followed by Aztreonam (53.19%), Ceftazidime (42.55%), Ceftazidime (42.55%) Ampicillin (32.97%) and Cefepime (19.14%). However, highest sensitivity was observed towards Cefepime + Clavulanic acid (86.17%) followed by Cefepime (80.85%), Amoxicillin + Clavulanic acid (77.65%) and Ampicillin + Sulbactam (71.27%). The sensitivity to other tested beta-lactam antimicrobials was observed below 40%. These findings can be utilized in mastitis treatment programmes and antimicrobials strategies in organized herds.

Keyword: Mastitis; E. coli; Beta-lactams; Resistance; Sensitivity;