Susceptibility of coagulase positive staphylococci isolated from cow's mammary gland to antibacterial drugs

Coagulase positive staphylococci are one of the most common causes of chronic udder infection. Indiscriminate use of antimicrobial drugs and their presence in the environment where animals live has led to coagulase positive staphylococci strains resistant to antimicrobial means. Proper and timely treatment of sub-clinical mastitis, based on the most effective use of antimicrobial drugs, is the key to good health of the milk herd. The aim was to determine the antimicrobial efficacy of selected assets in relation to coagulase positive staphylococci isolated from samples of milk taken from individual udder quarters of cows in cases of udder infection from three farms with different mastitis prevalence. From a total of 9245 samples of milk taken from individual udder quarters of cows from three farms, 852 strains isolated were coagulase positive staphylococci. Coagulase positive staphylococci were isolated on blood agar and identified on the basis of macro-morphological characteristics and the coagulase and catalase test. The sensitivity of the coagulase positive staphylococci was tested by the Kirby Bauer agar diffusion method with the following antimicrobials: penicillin 6µg, amoxicillin / sulbactam (20 +10µg), cloxacillin 25 µg, cefalexin 30 µg, ceftiofur 30µg, linkomycin 15µg, 30 µg gentamycin and tetracycline 30 µg. Sensitivity testing of coagulase positive staphylococci, isolated in cases of intramammary cow infections, established a high degree of sensitivity in vitro towards penicilinasa resistant drugs (amoxicillin-sublactam, cloxacilin), cephalosporins of the first and third generations and linkomycin. The highest levels of resistance to penicillin (70.4%) were found on a farm with a moderate prevalence of udder infection, then on the farm with the highest prevalence of intramammary infections (60.2%) and the lowest on the farm with controlled levels of resistance of infection (43.7%).