Methicillin-resistant Staphylococcus aureus in the hospitals of Central Greece

A total of 250 consecutive Staphylococcus (aureus clinical isolates were co llected during the period 1999-2000 from the five major hospitals of the di strict of Thessaly (Central Greece). Thirty seven (14.8%) of the isolates w ere mecA-positive (MRSA) in a PCR-based assays all exhibited resistance to oxacillin (agar dilution MICs greater than or equal to4 mg/L) and were also resistant to multiple antibiotics. Most of the MRSA isolates had been coll ected in the intensive care units and the surgical wards of the participati ng hospitals in a sporadic fashion. The MRSA incidence found here was signi ficantly lower than reported in previous studies from Greece. Molecular typ ing by PFGE showed that the MRSA isolates were distributed between three pu lsotypes. Evaluation of various conventional methods for assessing methicil lin resistance showed that oxacillin agar dilution and immunological detect ion of PBP2a with the Slidex MRSA Detection kit were the most reliable in t his setting. Misclassifications of isolates exhibiting low-level resistance (oxacillin MIC 2-4 mg/L) occurred with the salt agar screen, the oxacillin disk diffusion and the ATB Staph System methods. (C) 2001 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved.