Biotyping of Staphylococcus aureus strains isolated from humans and bovine raw milk samples in Hamedan province

Staphylococcus aureus causes a wide range of diseases in humans and animals. Rapid and precise typing of S. aureus is a prerequisite for epidemiological surveillance and controlling of infection caused by this bacterium. In this case, biotyping is a simple, cheap, and effective method for epidemiological investigations. A total of 143 S. aureus strains isolated from human (40 patient strains, 20 carrier strains) and bovine raw milk samples (83 strains from 7 herds) were genotypically confirmed by polymerase chain reaction (PCR), and phenotypically assessed using a biotyping method to determine the possible sources of contamination. Of 143 examined strains by the biotyping method, 14 strains belonged to human ecovars, while 11, 25, and 12 strains were classified as bovine, sheep, and poultry ecovars, respectively. Meanwhile, 61 strains were found to be non-host specific (NHS) biotypes, and 20 strains were not typable by this method. The results of the present study showed that in Hamedan province, humans and bovine raw milk samples were frequently contaminated by strains belonging to the K-B-CV:C biotype. However, among host specific (HS) biotypes, sheep ecovar was the most common biotype. The results indicated possibility of transmission of different ecovars among various species.