Profile of virulence genes of Staphylococcus aureus isolated from subclinical and clinical bovine mastitis in the Alborz province

The aim of this study was to determine virulence genes patterns of Staphylococcus aureus isolated from bovine subclinical and clinical mastitis. A total of 1,920 quarters of 480 dairy cattle in seven commercial dairy farms of Alborz province, Iran examined using CMT test. Staphylococcus aureuses were detected from clinical and subclinical samples with bacteriological culture. Based on coagulase reaction and 23sr DNA, a total of 33 and 12 strains of Staphylococcus aureus were isolated from subclinical and clinical mastitis cases respectively. The Staphylococcus aureus strains were characterized genotypically by polymerase chain reaction using oligonucleotide primers that amplified genes encoding clumping factor (clfA), coagulase (coa), the gene segments encoding the X region of protein A gene spa (SpaA-X), accessory gene regulator (agrIII), hemolysin A (hla), and hemolysin B (hlb). Based on a remarkable variability detected in the studied genes 17 different profiles were identified among the samples, indicating a great diversity of Staphylococcus aureus involved in the etiology of mastitis cases in this region. The predominant profile between subclinical and clinical cases was clfA, coa, agrIII. These results help in the understanding of the distribution of the prevalent Staphylococcus aureus strains among bovine subclinical and clinical mastitis isolates in Alborz province, and might contribute to the establishment of preventive strategies to decrease the spread of infection.