The genes for Panton Valentine leukocidin (PVL) are conserved in diverse lines of methicillin-resistant and methicillin-susceptible Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus isolated in the community (CA-MRSA) have been reported to carry the loci for Panton Valentine leukocidin (PVL) in high frequency. CA-MRSA in Orebro County, Sweden, constitutes at least 50% of MRSA and the PVL locus is detected in as many as 66% of these CA-MRSA isolates. The aim of this study was to characterize PVL-positive methicillin-resistant and methicillin-susceptible Staphylococcus aureus by molecular methods, to determine the nucleotide sequence of lukS-PV and lukF-PV in S. aureus isolates of different origins, and to investigate the biological consequence of variations occurring in the genes. The PVL-positive MRSA investigated were composed of six different STs (ST8, 36, 80, 152, 154, and 256). Six additional STs (ST5, 22, 25, 30, 88, and 567) were detected when investigating PVL-positive methicillin-susceptible S. aureus with MLST. Despite the different genetic origins of the isolates analyzed, the PVL genes were well conserved and only one mutation was non-synonymous. Evaluation of the consequence of this mutation showed that the mutated toxin and wild-type toxin had comparable biological activity on human polymorphonuclear cells.