Staphylococcus aureus is an important pathogen characterised by its potential to express many virulence factors. Currently, special attention is being paid to methicillin-resistant strains of S. aureus (MRSA). The aim of this study was to compare the prevalence of 13 selected virulence factor genes in methicillin-resistant versus methicillin-susceptible S. aureus (MSSA) isolates and to investigate their accumulation in the same isolate. Real-time PCR was used to detect the presence of genes in 200 isolates of S. aureus (100 MRSA and 100 MSSA) from the University Hospital Olomouc collected in 2005-2006. Six out of the 13 monitored genes were detected more frequently in MRSA isolates: sea, seb, seg, sei, sej and eta, coding for the production of the enterotoxins A, B, G, I, J and the exfoliative toxin A. On the other hand, the pvl and tst genes coding for Panton-Valentine leukocidin and TSST-1 were more frequent in MSSA. Statistical analysis (chi-squared test) of the prevalence of virulence factors in the two groups showed a significant difference (P<0.05) in two cases (seg, sei). A higher prevalence of selected virulence genes was not confirmed in the methicillin-resistant S. aureus group. This indicates no further increase in their threat.
