Antimicrobial resistance of isolates of microorganisms identified in the milk of cows with subclinical mastitis in the ural region of Russia

During 2017 n = 375 milk samples of dairy cows with subclinical mastitis from 18 farms of the Ural Region were examined in order to identify the main pathogenic agents and their antimicrobial resistance. Microbiological research on the milk using real time PCR using the device Rotor Gene-3000 (Australia), with the complex of reagents of the IDS company (Russia) was done, to identify DNA from biological material and determine antimicrobial resistance of microorganisms. The identified microorganisms included: Staphylococcus spp. –77.3%, E. coli – 37.3%, S. aureus – 38.7%, S. agalactiae – 14.7%. Associations of microorganisms included: S. aureus, Staphylococcus spp. – 17.3%; Staphylococcus spp., E. coli – 21.3%; S. agalactiae, E. coli – 2.7%; St. aureus, Staphylococcus spp., E. coli – 8.0%; S. aureus, Staphylococcus spp., S. agalactiae – 2.7%; S. aureus, Staphylococcus spp., S. agalactiae, E. coli – 1.3%. The gene of CTX-M that determines resistance of Enterobacteriaceae to Cephalosporin of the 1st generation was found in 3.6% of samples with E. coli. The gene of blaDHA that determines resistance of Enterobacteriaceae to penicillin and cephalosporin of the 3rd and 4th generations was found in 4.6% samples with E. coli.. 3.6% of the samples with E. coli had two mutational genes CTX-M and blaDHA. The gene MecA that determines resistance of S. aureus to Cephalosporin of the 2nd generation was found in 10.6% samples. Resistance of Staphylococcus spp. and Streptococcus spp. to macrolides of the 1st generation (the gene of ErmB) was identified in 45.3% samples. In conclusion, the research done proved the wide spread of antimicrobial resistance of pathogenic agents causing subclinical mastitis in dairy cows