Detection of the Panton-Valentine Leukocidin Gene in Swedish Isolates of Methicillin-Resistant Staphylococcus aureus using a Multiplex PCR Assay

Background: Panton-Valentine leukocidin (PVL) is a bicomponent leukotoxin produced by <2% of Staphylococcus aureus (S. aureus) strains. PVL forms transmembrane pores that cause cell disruption and death. PVL is associated with skin necrotic lesions and severe necrotizing pneumonia. The methicillin-resistant S. aureus (MRSA) strains that harbor the lukS-PV gene (the gene encoding PVL toxin) are considered highly pathogenic since they can cause infections that are difficult to treat. Objective: This study aimed to optimize a multiplex PCR assay that can detect both methicillin-resistant S. aureus strains and their ability to produce PVL toxin isolated from Swedish patients. Methods: An optimized multiplex PCR-assay was developed to detect both nuc and lukS-PV genes and was applied to a collection of 80 MRSA clinical isolates collected between 1999 and 2004. Results: The results showed that 30/80 (40%) of all MRSA isolates were PVL-positive. The highest PVL prevalence (86%) was among abscess isolates. When PVL was correlated to staphylococcal protein A (spa) typing, the highest PVL positivity was among spa-type 44. Conclusion: The results of this study showed that the lukS-PV gene is common among Swedish community of the MRSA isolates.