Genetic characterization of Panton-Valentine leukocidin-producing methicillin-resistant Staphylococcus aureus in Western Austria

Community-acquired methicillin-resistant Staphylococcus aureus (caMRSA) is an emerging pathogen which causes potentially severe infections in young and healthy individuals due to the ability of most strains to produce Panton-Valentine leukocidin (PVL). The aim of this study was to evaluate the prevalence of PVL-positive (PVL+)-MRSA strains in Western Austria in the period from December 2005 to May 2010 and to characterize the identified PVL+-MRSA strains. Six hundred and fifty MRSA strains from Innsbruck Medical University hospital, district hospitals, and general practitioners were investigated for the presence of lukS-lukF gene (encoding for PVL). Antimicrobial resistance testing, SCCmec-, agr-, MLST- and spa-typing, as well as arcA determination were performed on PVL+-MRSA. Among 650 MRSA strains collected from various body sites from hospitalized patients and outpatients, 31 strains (4.8 %) were positive for lukS-lukF and thus identified as PVL+-MRSA. Agr-1 was the most common agr-type (n = 18, 58.1 %) and SCCmec-IV or variants IVa and IVc were the most common SCCmec types (n = 27, 87.1 %). All tested strains showed in-vitro susceptibility to vancomycin and rifampicin, but resistance against cotrimoxazol (6.4 %), clindamycin (9.7 %), gentamicin (9.7 %), fusidic acid (12.9 %), levofloxacin (12.9 %), and erythromycin (61.3 %) was found. Most lukS-lukF-positive MRSA detected in our survey shared ST8 and t008 and were positive for arcA. The major lukS-lukF-positive MRSA lineage found in our population was ST8, t008 and positive for arcA which is mainly found in the USA. In contrast, ST80 strains were not found as frequently in our region as in many other European countries.