109 ISSN 0891-4168, Molecular Genetics, Microbiology and Virology, 2016, Vol. 31, No. 2, pp. 109–115. © Allerton Press, Inc., 2016. Cassette Chromosome mec Typing of Methicillin-Resistant Staphylococcus aureus Isolates from Patients in Tehran 1 R. Ranjbar a, *, M. Moazzami Goudarzi b, **, N. Jonaidi c, ***, and R. Moeini d, **** a Molecular Biology Research Center, Baqiyatallah University of Medical Science, Tehran, Iran b Department of Microbiology, Faculty of Basic Science, Islamic Azad University, Science and Research Branch, Tehran, Iran c Health Research Center, Baqiyatallah University of Medical Science, Tehran, Iran d Department of Microbiology, Jahroum Branch, Islamic Azad University, Jahroum, Iran *e-mail: Ranjbarre@gmail.com; **e-mail: moma1675@gmail.com; ***e-mail: md.researcher@yahoo.com; ****e-mail: goudarzi.bastani@gmail.com Abstract—Background: Methicillin-resistant Staphylococcus aureus is the 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 clinical specimens from Iranian patients 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 by SPSS-18 software. Results: Disk agar diffusion test using cefoxitin disk (30 μg) showed methicillin resistance in 59% of our iso- lates. 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%), SCC- mecIVc (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 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 prop- agating CA-MRSA isolates in the studied hospitals. Keywords: Methicillin-resistance Staphylococcus aureus, Cefoxitin, SCCmec typing, Multiplex PCR, femB, mecA DOI: 10.3103/S0891416816020087 INTRODUCTION The resistance of microorganisms to antimicrobial factors is a growing problem and a global challenge. Drug resistant bacteria in hospitals and communities is a common cause of concern as it leads to treatment failure, increase in diseases and mortality. Staphylo- coccus aureus is animportant cause of serious infection in the hospitals and communities. Methicillin, the first synthetic penicillin, was used in 1961 for the treat- ment of S. aureus infections. The first methicillin- resistant S. aureus was identified in England at the same year. Infections caused by MRSA strains leads to high mortality. These organisms acquired resistance to a broad group of beta-lactam antimicrobial factors increasing in the world [1]. A study in America, compared the patients who were not infected by S. aureus, with those suffered from Staphylococcal infection. This study showed that mortality rate in Staphylococcal group was five times more than non-staphylococcal group, and in respect, the cost of hospitalization and cost of additional treat- ment would be three times more in the comparison with non-Staphylococcal group [2]. Recently, the MRSA strains have been divided into two subgroups: the MRSA acquired from therapeutic environment (Health Care Associated-MRSA) and acquired from commu- nity (Community Associated-MRSA). HA-MRSA is the main problem of hospital infections, and it was seen in patients who were in hospitals for more than 48 hours. The high risk factors for HA-MRSA includes patients with open wound or foreign object or immu- nodeficiency. On the other hand, the CA-MRSA strains, in recent years, have become an increasing major concern for public health. CA-MRSA strains have been 1 The article is published in the original. EXPERIMENTAL WORKS