Abstract: [Objective] To understand the types of pathogens causing mastitis in dairy cows in Tianshui,Gansu and their sensitivity to drugs.[Method] 40 milk samples from clinical mastitis cows from 3 dairy farms in Tianshui,Gansu were selected,and pathogenic bacteria were isolated and identified using culture medium method and biochemical analysis method,respectively. Kirby Bauer disk diffusion method was used to conduct in vitro drug sensitivity test on the isolated pathogenic bacteria. [Result] Among 140 strains of bacteria isolated,Escherichia coli,Staphylococcus aureus and Streptococcus agalactis accounted for 32.1%,27.2% and 14.3% respectively. The results of drug sensitivity test showed that 45 strains of Escherichia coli were resistant to penicillin,and the drug resistance rate was as high as 100%,while Escherichia coli was the most sensitive to Vancomycin,and no drug resistance was detected in 45 strains.[Conclusion] Provide a certain theoretical basis for the prevention and treatment of mastitis in Gansu Tianshui dairy cows.

Key words: cow mastitis, bacterial pathogens, isolation and identification, Escherichia coli, drug sensitivity test