Background: Panton-Valentine Leukocidin (PVL) is accepted as a marker of disease severity in staphylococcal infections. In this study we have determined the prevalence of PVL genes among Staphylococcus aureus isolated from paediatric patients with bacteraemia.
Methods: Non-duplicate S. aureus isolated from patients with bacteraemia collected from 2004 to 2008 were examined. PVL genes were screened by a PCR protocol (lukS and lukF). Oxacillin-resistance and identification was confirmed using a multiplex PCR to detect mecA and nuc genes. The clonality of PVL-positive isolates was determined using an automatic RiboPrinter®.
Results: A total of 15 oxacillin-resistant (MRSA) and 109 oxacillin-sensitive (SAMS) S. aureus were isolated over the 4.5 year interval (12.1%). Only 2 strains of MRSA were of the multi-resistant hospital clone common in Australia, ST239, resulting in 10.5% of bacteraemias being caused by community-MRSA. PVL genes were detected in 10.1% of MSSA and 26.7% of SAMR during the study period. The prevalence of PVL in MRSA reflected the proportion of community-acquired MRSA types harbouring PVL in South Australia.
Conclusions: PVL positivity is common among bacteraemia isolates in paediatric patients in South Australia, even in oxacillin-susceptible strains and is higher than the putative background rate of PVL in community MSSA generally. PVL positivity in bacteraemic MRSA reflects the prevalence of PVL-positive clones of community-MRSA (ST93 and ST30) in South Australia.