Observations of fenotipic and genotipic resistance for Staphylococcus aureus in milkers

Abstract

Staphylococcus aureus is recognized worldwide as one of the major agents of dairy cow intra-mammary infections and cause a wide variety of clinical diseases in humans. Staphylococcus aureus can be transferred during milking from milkers (especially from their hands that come into contact with the udder) to cows. The exchange of resistance genes is very effective during colonization or infection of host organisms. The aim of this study was to determine the prevalence of Staphylococcus aureus isolated from the nasal cavities of milkers. In this study were taken 30 samples from nostrils of milkers and 66.6% of them were confirmed as Staphylococcus aureus. For these isolates, 25 antibiotics were tested using the PBC29 panel and all isolates (100%) were found to be resistant to ampicillin and penicillin. Through the qPCR reaction, 6 resistance genes (blaZ, cfr, ermB, ermC, mecA, and tetK) were tested and 13 antibiotics were associated with them. For each gene it was calculated the penetrance (P%) and diagnostic odds ratio (DOR) to see if the phenotypic expression of resistance/susceptibility is also found in genes. In this study, overall penetrance was P%=52%, the penetrance had values between 22% (tetK) and 80% (blaZ) and DOR had superunitary values in mecA gene (DOR=1.21), cfr (DOR=1.53), ermB (DOR=2.54) and ermC (DOR= 5.44).This approach can enhance the understanding of plasmidborne resistance and improve diagnostic accuracy, ultimately contributing to better management of antimicrobial resistance in veterinary settings.