ANALYSIS OF THE ANTIBIOTIC RESISTANCE GENES OF MICROORGANISMS IN THE MILK OF COWS AND GOATS

In 2018, 158 cow milk samples and 21 goat milk samples from animals with subclinical mastitis from various farms in five regions of Russia were examined. The objective of the research was to identify DNA of pathogenic bacteria in the milk and to determine the presence of antibiotic resistance genes. We have conducted PCR studies of the biological material on the device “RotorGene-3000” (Australia), using a set of reagents “IDS” (Russia). In 94.3% of cow milk samples, the DNA of the following microorganisms was detected: Staphylococcus spp. (73.4%), S. aureus (23.4%), E. coli (34.1%), S. agalactiae (12.0%). The blaDHA gene, which determines resistance to inhibitor-protected penicillins and cephalosporins of the 3rd and 4th generations, was found in 83.0% of E. coli. Antimicrobial resistance of S. aureus against 2nd generation cephalosporins (MecA gene) was found in 29.2% of the samples. The gene of resistance to macrolides of the 1st generation (ErmB) was found in 20.0% of Staphylococcus spp. and 2.7% of S. agalactiae. Resistance gene for 1st generation cephalosporins (CTX-M) was found in 3.3% of E. coli. In 71.4% of goat milk samples, the following specific microbial DNA was detected: Staphylococcus spp. (23.8%), S. aureus (38.0%), E. coli (42.8%), S. agalactiae (9.5%). The blaDHA gene was found in 90.0% of E. coli. These data indicate a widespread antibiotic resistance of pathogenic agents in the milk of cows and goats. The high prevalence of blaDHA gene positive samples could be associated with the frequent use of penicillins and cephalosporins of the 3rd and 4th generations on the farms. Laboratory control of bacterial resistance to antibiotics is required. Improvement of udder health management including vaccines or alternative antibiotics should be considered