RESUMEN
Backgrounds and Objectives: Methicillin-resistant Staphylococcus aureus is a cause of nosocomial infections leading to high mortality. Since these strains have become prevalent in the world, it is necessary to identify and type them
Materials and 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 in 2012-2013. 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. SCCmec typing was performed by multiplex PCR method and the results were analyzed using chi-square tests using SPSS-18 software
Results: Disc agar diffusion test using cefoxitin disc [30 microg] showed methicillin resistance in 59% of our isolates. mecA and femB genes were identified in all of the MRSA isolates 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 were HA-MRSA, 3% were CA-MRSA and 15% were Non-typeable
Conclusion: In our S. aureus isolates, 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 propagating CA-MRSA isolates in the studied hospitals