Molecular Characterization and SCCmec Typing in Methicillin-Resistant Staphylococcus aureus Isolated from the Staff in Zanjan Tertiary Hospitals

Background and Methicillin-resistant Staphylococcus aureus (MRSA) isolates are the most common pathogen that causes hospital and community acquired infections. Studying on drug resistance, it is important strategy to prevent these types of infections. The use of molecular typing methods is essential for determining the origin of the strains and also in epidemiological investigations. The aim of present study was to survey the molecular characteristics of Staphylococcus aureus (SA), to detect mecA gene, and typing SCCmec in the strains isolated from staffs in Vali-aser and Mousavi hospitals in Zanjan province. This descriptive study was carried out on 104 SA isolates collected from the clinical samples at Vali-aser and Mousavi hospitals. The identification of all tested isolates were confirmed by Gram's stain, coagulase and manitol salt agar and the isolates were tested for antibiotic resistance by the disc-diffusion method. In addition, the genotypes of SCCmec in the MRSA isolates were determined by multiplex PCR and the results were analyzed using the chi-square. The highest resistance was shown against oxacillin, penicillin, tetracyclin and co-trimoxazole and the most sensitive antibiotics were amikacin and ciprofloxacin and all of the isolates were sensitive to vancomycin and all of the isolates were resistant to at least three classes of antibiotics. Five (8.6%) MRSA strains were SCCmec type I, 11 (19%) were type II, 20 (34.5%) were type III, 17 (29.3) were type IV-a, 1 (1.7%) were type IV-b, 2(3.4%) were type IV-c, 11 (19%) were type IV-d and 18(31%) were type V. Overall, 19 (32.7%) MRSA strains could not be typed. Our findings show that clinical isolates of MRSA in our hospital carrying various types of staphylococcal cassette chromosome mec (SCCmec) types. SCCmec typse III and V were the predominant strain of MRSA identified.