Characterization of SCCmec types and antibacterial susceptibility patterns of methicillin-resistant Staphylococcus...

A total of 156 methicillin-resistant Staphylococcus aureus (MRSA) isolates from patients hospitalized in southern Iran were tested for staphylococcal cassette chromosome mec (SCCmec) types and antibacterial susceptibility patterns between May 2008 and May 2009. Type III SCCmec was the most prevalent (116, 74.3%), followed by mec types A (147 bp only; 11, 7.1%), IVa (8, 5.1%), IVc (7, 4.5%), IVd and V (4, 2.6%), and II (1, 0.6%). Class A mec and type III ccr and mec complexes were also predominant. All isolates were found to be sensitive to vancomycin, teicoplanin, linezolid, quinupristin-dalfopristin, mupirocin, and fusidic acid. However, reduced sensitivity of these MRSA isolates to other antibiotics, including rifampin, co-trimoxazole, clindamycin, cephalexin, tetracycline, ciprofloxacin, erythromycin, and gentamicin, was also observed. The predomination of type III SCCmec could be due to the antibiotic pressure which facilitated its clonal selection and dissemination. The present findings are indicative of the existence of community-acquired types (IV, V) in the hospitals studied, therefore comprehensive and periodic control measures and rational prescription of appropriate antibiotics are highly recommended to reduce antibiotic resistance.