Virulence gene profiles inStaphylococcus aureusisolated from cows with subclinical mastitis in eastern Poland

Abstract

Staphylococcus aureusis arguably the most important pathogen involved in bovine mastitis. The aim of this study was to determine the virulence gene profiles of 124Staph. aureusisolates from subclinical mastitis in cows in eastern Poland. The presence of 30 virulence genes encoding adhesins, proteases and superantigenic toxins was investigated by PCR. The 17 different combinations of adhesin genes were identified. Occurrence ofeno(91·1%) andfib(82·3%) genes was found to be common. The frequency of other adhesion genesfnbA, fnbB, ebpswere 14·5, 50, 25%, respectively, and forcnaandbbpwere 1·6%. TheetAandetDgenes, encoding exfoliative toxins, were present in genomes of 5·6 and 8·9% isolates, respectively. ThesplAandsspA, encoding serine protease, were detected in above 90% isolates. The most frequent enterotoxin genes weresei(21%),sem(19·4%),sen(19·4%),seg(18·5%) andseo(13·7%). Thetstgene was harboured by 2·4% isolates. The 19 combinations of the superantigenic toxin genes were obtained and found in 35·5% of isolates. Three of them (seg, sei, sem, sen, seo; sec, seg, sei, sem, sen, seoandseg, sei, sem, sen) were the most frequent and found in 16·1% of the isolates. The most common virulotype, present in 17·7% of the isolates, wasfib, eno, fnbB, splA, splE, sspA. The results indicate the variation in the presence of virulence genes inStaph. aureusisolates and considerable diversity of isolates that are able to cause mastitis in cows.