Panton-Valentine leukocidin gene detected in a Staphylococcus aureus strain isolated from a knee arthroprosthesis infection

This report focuses on the molecular characterization of a Staphylococcus aureus strainisolated from a knee arthroprosthesis infection and recognized retrospectively as a carrier of the Panton-Valentine leukocidin gene. The stored microbiological isolate, which belonged to the strain collectionof the Research Unit on Implant Infections of the Rizzoli Orthopaedic Institute, was retrievedfor molecular analysis. Genotyping was carried out, revealing an interesting profile. In addition tothe positivity for the Panton-Valentine toxin gene, the results indicated that the isolate belonged tothe agr III group and was endowed with bbp and cna genes, both encoding for staphylococcal adhesinsthat bind bone proteins. The strain had the mecA gene for methicillin resistance, even thoughit was unable to resist any of the β-lactam or other antibiotics. Its gene configuration matched thatof other community-acquired methicillin-resistant and methicillin-susceptible Staphylococcus aureus(CA-MRSA and CA-MSSA) strains which have recently been reported worldwide. As far as we know,this is the first report on a PVL-positive S. aureus strain associated with an orthopedic implant (kneearthroprosthesis) infection.