Genetic diversity and virulence factors of Staphylococcus aureus strains isolated from bovine udder skin

Abstract

Staphylococcus aureus is a pathogen recognized as a cause of mastitis in cattle worldwide, so the objective of this work was to determine the presence of Staphylococcus aureus in the teat skin of the bovine udder and relate it to the presence of mastitis, as well as to determine the virulence factors and genetic diversity of the strains. Samples of 250 milking cows were taken in three farms, in two seasons of the year, dry and rainy. In addition, the California test was performed. Staphylococcus aureus was isolated in salt agar and mannitol and biochemically identified and confirmed with amplification of the femA gene. For the identification of virulence factors, the genes hlB, mec, saK, pvL, tsst-1, seA, seB, seC, seD and seE were used by end-point PCR. For the typing of S. aureus, amplification and restriction of the coag gene was performed. The frequency of S. aureus was 13.4 %. No statistical relationship between the presence of S. aureus in the bovine udder skin and the development of subclinical mastitis was found. The most frequent enterotoxin gene in the strains was enterotoxin A. Although the percentage of typing is low, it was possible to identify two restrictotypes that group strains isolated from different cows, which shows the infectious and contagious capacity of the microorganism.