Phenotypic and genotypic resistance to antibiotics in strains isolated from cattle milk in Northern Kazakhstan.

BACKGROUND AND AIM

is the most frequent and ubiquitous cause of mastitis in cows. In recent decades, antibiotic resistance has rapidly spread among infectious disease pathogens in Kazakhstan and globally. This study examined the phenotypic and genotypic resistance of . strains obtained from cattle milk to antibiotics.

MATERIALS AND METHODS

In 2021 and 2022, 675 cow milk samples were collected from 16 dairy farms in Northern Kazakhstan. was identified using culture and biochemical methods. The nature of antibiotic resistance was determined by the disk diffusion (DD) method. The distribution of antibiotic resistance genes was determined by polymerase chain reaction.

RESULTS

Among the obtained isolates, high levels of resistance to β-lactam antibiotics (100%), tetracyclines (95.4%), fluoroquinolones (95.4%), and macrolides (60.92%) were observed. Meanwhile, the lowest levels of resistance were identified for sulfonamides (21.84%) and aminoglycosides (27.59%). All the obtained isolates were positive for the gene encoding thermonuclease. The , , and genes were detected in 45.9%, 77%, and 83.9% of the studied isolates, respectively.

CONCLUSION

The results indicate a high prevalence of antibiotic resistance in isolated from cows with clinical and subclinical forms of mastitis in Northern Kazakhstan. In addition, the prevalence of resistance was higher when evaluated by the DD method than when detecting the specific antibiotic resistance genes , , and , indicating the need for deeper analysis of the phenotypic and genetic determinants of antibiotic resistance.