Panton-Valentine leukocidin in pediatric community-acquired Staphylococcus aureus infections.

PURPOSE Panton-Valentine Leukocidin (PVL) is an exotoxin produced by strains of Staphylococcus aureus (SA). Its importance as a virulence factor is controversial. We aim to further characterize the role of PVL in pediatric community-acquired SA infections. METHODS In a cohort study conducted from July to November 2006, we prospectively collected all strains of SA isolated at the Montreal Children's Hospital causing community-acquired infections in children aged 18 years or younger. The strains were analyzed for the presence of the PVL encoding genes by PCR and were phage typed. Strains resistant to methicillin or pvl+ were analyzed by pulsed-field gel electrophoresis. A medical chart review blinded to patient pvl status was performed to retrieve demographic and clinical data. Data were analyzed by logistic regression. RESULTS We identified 74 pediatric community-acquired SA infections. Nineteen strains (25.7%) were positive for the pvl genes. Four isolates (5.4%) were resistant to methicillin and three of these were pvl+. No predominant clone was identified by phage typing or pulsed field gel electrophoresis. Pvl+ and pvl- infections were statistically similar for patient age, hospital admission, length of hospital stay, invasive disease, intravenous antibiotics and outcomes. Pvl+ strains were more likely to cause abscesses (OR 20.79; 95% CI 4.93 - 87.58), less likely to cause superficial skin infections (OR 0.18; 95% CI 0.05 - 0.64) and less likely to be resistant to erythromycin (OR 0.048; 95% CI 0.004 - 0.52). CONCLUSIONS In a clonally heterogeneous population of pediatric community-acquired SA infections, pvl+ strains were associated with abscess formation and erythromycin susceptibility, but not invasive disease.