PHENO-GENOTYPIC DETERMINANTS OF ANTIBIOTIC RESISTANCE AND VIRULENCE IN ESCHERICHIA COLI BACTERIA ISOLATED FROM THE MILK OF COWS WITH SUBCLINICAL MASTITIS

The traditional antibiotic therapy for cow mastitis often leads to the emergence of mono- and multi-resistant strains of microorganisms. Therefore, elucidating the etiological role of antibiotic-resistant E. coli cultures in the pathogenesis of subclinical mastitis is an urgent problem of theoretical novelty and practical significance. The purpose of the study is to explore the pheno-genotypic characteristics of antibiotic resistance and virulent properties of Escherichia coli bacteria isolated from the milk of cows with subclinical mastitis. Diagnosis of subclinical mastitis was carried out using generally accepted methods. Sensitivity to antibacterial drugs was determined by the disk diffusion method. As a result of the studies, it was found out that Escherichia coli cultures were isolated in 59% of milk samples from cows with subclinical mastitis. The isolated cultures were resistant to some antibiotics of the aminoglycoside group (kanamycin, gentamicin, amikacin, tobramycin and streptomycin), 2nd generation fluoroquinolones (ciprofloxacin) and tetracyclines. The molecular genetic studies showed that fimA virulence genes were detected in 95,74% of isolated E. coli cultures, and fimH genes were detected in 81.91% of cultures. They encode adhesion proteins of E. coli to endothelial cells. The study of pharmacodynamic mechanisms of resistance revealed the production of extended spectrum beta-lactamases in 69,14% of E. coli cultures. In addition, this work was one of the first attempts to show the widespread prevalence of antibiotic-resistant E. coli cultures in subclinical mastitis in the region. Sponsorship information. This work was carried out within the framework of a grant from the Russian Science Foundation (Agreement No. 23-26-00118, dated January 13, 2023)