Comparison of the prevalence of genes coding for enterotoxins, exfoliatins, panton-valentine leukocidin and tsst-1 between methicillin-resistant and methicillin-susceptible isolates of Staphylococcus aureus at the university hospital in olomouc.

AIMS

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.