[Investigation of SCCmec types and Panton-Valentine leukocidin in community-acquired and nosocomial Staphylococcus aureus strains: comparing skin and soft tissue infections to the other infections].

Infections due to methicillin-resistant Staphylococcus aureus (MRSA) are important health care problems since they are usually multidrug resistant. Although MRSA is isolated especially from nosocomial infections, community-acquired MRSA infections are increasing. Methicillin resistance is due to the expression of mecA gene, which is located on SCCmec gene cassette. Different SCCmec types can be detected in hospital-acquired and community-acquired (CA-) MRSA strains. CA-MRSA strains might harbour Panton-Valentine leukocidin (PVL), an important virulence factor in skin and soft tissue infections. Strains carrying PVL has the ability to penetrate undamaged skin and cause more severe infections. The aim of this study was to detect SCCmec types and PVL gene in S.aureus strains isolated from skin and soft tissue infections and to compare with strains isolated from other infections in a university hospital in Ankara, Turkey. S.aureus strains isolated from skin and soft tissue infections (n= 285) and a control group consisting of 161 strains isolated from other infections (53 blood, 48 lower respiratory tract samples, 30 sterile body fluids, 30 genitourinary tract samples) chosen by stratification and random selection method, were included in the study. Among skin and soft tissue infection strains 46.7% were from the hospitalized patients and 48.4% of skin and soft tissue infection strains were from female patients. The mean age of the skin and soft tissue infection patients was 45.5 years. Among the control strains 60.9% were from the hospitalized patients and 41.6% of the control patients were female. The mean age of the control patients was 50.2 years. Strains were identified by the Phoenix system (Becton Dickinson, USA) and identification was confirmed by tube coagulase test. Methicillin resistance was determined by the Phoenix system which determines both oxacillin and cefoxitin minimum inhibitor concentrations and, confirmed by oxacillin agar screening and/or cefoxitin disk diffusion test. All isolates were screened for the presence of mecA and PVL genes and SCCmec types were determined by PCR. MRSA constituted 20.3% (n= 58) of skin and soft tissue infection isolates and 24.2% (n= 39) of the control group. Of the 97 MRSA, 85 had a SCCmec type III-like pattern with an additional dcs region, three had type IV, three had type IIIa, one had type IIIb, one had type II and four could not be typed. The difference between SCCmec type distribution in skin and soft tissue infection and other infections' (control) groups was not statistically significant (p> 0.05). Two of the three SCCmec type IV strains were type IVa. Ten (2.2%) PVL positive strains, three of which were from the control group; were all methicillin susceptible S.aureus (MSSA). Although PVL positive MRSA was not common, detection of SCCmec type IVa, a marker for CAMRSA, and PVL positive MSSA strains which might act as a reservoir for PVL positive MRSA, indicated the importance of ongoing surveillance for MRSA.