The Staphylococcal Cassette Chromosome mec (SCCmec) Analysis and Biofilm Formation of Methicillin-resistant Staphylococcus cohnii Isolated from Clinical Samples in Tehran, Iran

Background: Methicillin-resistant coagulase-negative staphylococci is responsible for hospital and community-acquired infections. Objective: This study aimed to investigate the antibiotic-resistance patterns, antibiotic-resistance genes, namely, ermA, ermB, ermC, blaZ, msrA, tetK, tetM, mup, and vanA, biofilm formation, and prevalence of different SCCmec types among the Staphylococcus cohnii strains isolated from clinical samples in Tehran, Iran. Methods: In this study, S. cohnii isolates were screened from the clinical samples from March 2012 to February 2013 in Tehran, Iran. Antimicrobial susceptibility test and inducible clindamycin resistance were evaluated by disc diffusion method, and resistance genes were examined using Polymerase Chain Reaction (PCR) assays. Then, biofilm formation assay was analyzed by Microtiter-plate test to detect the icaA and icaD genes. The SCCmec and the Arginine Catabolite Mobile Element (ACME) typing were performed using the PCR method. Results: From twenty S. cohnii, all isolates were resistant to cefoxitin. 95% of the S. cohnii was defined as Multidrug Resistance (MDR) strains. The ermB, ermC, and vanA genes were not detected in any isolates; however, the blaZ gene had the highest frequency. 95% of the S. cohnii isolates produced biofilm. Also, 4 SCCmec types, including V, IV, III+ (C2), VIII+ (AB1), were identified. Therefore, the majority of SCCmec were untypable. Based on the ACME typing, arcA and opp3 genes were positive in 13 (65%) and 1 (5%) isolates, respectively. Conclusion: Due to the high antimicrobial resistance and the spread of untypable SCCmec among the isolates studied, the control and treatment of methicillin-resistant S. cohnii in hospitals and public health centers is a significant concern.