Peyman Bohlouli - Department of Genetics, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
Mohammad RezaNahaei - Department of Microbiology, School of Medicine, Tabriz University of Medical Sciences& Department of Microbiology and Laboratory Sciences, Tabriz Branch, Islamic Azad University, Tabriz, Iran

Background: Methicillin-resistant Staphylococcus aureusis a cause ofnosocomial infection leading to high mortality.Since these strains have become prevalent in the world, it is necessary to identify and type them. Methods: This cross-sectional study was conducted to study a total of 1475 specimens collected from patients of Imam Reza and Sina hospitals of Tabriz. Using phenotypic tests such as Gram stain, catalase, coagulase, DNase and mannitol fermentation 169 isolates of Staphylococcus aureus and by utilizing methicillin-resistance test 100 MRSA isolates were identified. SCCmectyping was performed by multiplex PCR method and the results were analyzed using chi-square tests by SPSS-18 software. Results: Disc agar diffusion test using cefoxitin disc (30 µg) showed methicillin resistance in 59% of our isolates.mecA and femB genes were identified in all of the MRSA isolates by using PCR method. Frequency of SCCmec types and sub-types were as follow: SCCmecIII (77%), SCCmecI (5%), SCCmecIVa (1%), SCCmecIVc (1%), mixed isolates SCCmecIVc-III (1%) and Non typeable isolates (15%). Non typeable isolates recovered in two groups (10% without any band and 5% of multi-bands III-I). In this study, 82% of isolates wereHA-MRSA, 3% were CA-MRSA and 15% were Non-typeable. Conclusion: In our Staphylococcus aureusisolates, the prevalence of methicillin resistance was 59%. The most frequent SCCmec type was SCCmecIII (77%). Our results demonstrated the spread of HA-MRSA isolates in the community and CA-MRSA isolates in the studied hospitals.

Methicillin-resistant Staphylococcus aureus, SCCmec, Multiplex PCR, femB gene, mecA gene