Antimicrobial resistance of clinical mastitis pathogens in cows on dairy farms in Ternopil region

Antibiotic-resistant microorganisms on dairy farms are currently considered new contaminants posing a serious threat to public health worldwide. The objective of this paper was to identify the main clinical mastitis pathogens in cows on dairy farms in Ternopil region and their resistance to antimicrobial agents. Staphylococci recovery was performed on BD Baird-Parker Agar, enterobacteria – on Endo agar, streptococci – on Streptococcus Selection Agar, fungi – on Sabouraud, and their identification was done according to Bergey’s Manual of Determinative Bacteriology (9th edition). Antibiotic sensitivity of mastitis pathogens was determined by the disc diffusion test, and the bacterial effect of anti-mastitis agents was determined using radial diffusion in agar. It was found that the main clinical mastitis pathogens in cows on dairy farms in Ternopil region were microorganisms of Staphylococcus genus, for instance, 38 % of all cases. Staphylococcus aurelius caused mastitis 1.9 time (Р ≤ 0,01) more often than other pathogenic staphylococci. E. coli microorganisms were recovered from the sick cows secretion 1.5 times (Р ≤ 0,05), and Str. dysgalactiae – 1.6 times (Р ≤ 0,05) less, compared with staphylococci. Str. dysgalactiae microorganisms were resistant almost to all antimicrobial agents, Staphylococcus spp. to 7 (33.3 %) and E. coli to 9 (42.9 %) agents out of 21 tested. The highest resistance of mastitis pathogens on dairy farms was found to tetracycline family antibiotics, such as tetracycline and doxycycline (63.4–97.6 %), β-lactam antibiotics of penicillin and ampicillin (100 %), as well as lincomycin (100 %), chloramphenicol (92.9–100 %), ceftazidime (67.9–97.6 %). Therefore, it is proposed to use antibiotics of no more than two pharmacological groups to treat mastitis, endometritis and other diseases of dairy cows during the year, followed by replacing them with new agents after preliminary recovery of mastitis pathogens and determination of antibioticogram.