Epidemiological Link between Methicillin-resistant Staphylococcus aureus Strains Isolated from 2 Different Cities in Iran

Background and Objectves: Methicillin-resistant Staphylococcus aureus (MRSA) strains are known as one of the most important multidrug-resistant organisms causing infections in humans and animals. The objectives of this experimental study were to characterize the clonality and antibiotic resistance of MRSA strains isolated from patients in two different cities in Iran. Materials and Methods: During 2015-2017, a total of 536 S. aureus isolates were collected from 2 reference hospitals in Tehran and Isfahan and were identified as MRSA using specific primers. The antibiotic susceptibility and their clonality were determined using the PhP typing system. Furthermore, the presence of different classes of prophages as well as the structure of staphylococcal cassette chromosome mec (SCCmec) elements and cassette chromosome recombinases (ccr) types were characterized. Results: Out of the 536 strains, 129 MRSA were identified using species-specific primers and discriminated into 26 PhP types consisting of 12 common types (CTs) and 14 single types (STs), in which CT2 was the predominant type and 6 CTs were common among MRSA isolated in both cities. SCCmec types III and IV were also detected in 89 and 11% of the strains and SGF prophage type was the dominant one. Thirty-four antibiotic patterns were detected among the MRSA strains and none of the isolates showed resistance to linezolid, quinupristin-dalfopristin, and vancomycin. Conclusion: High prevalence of antibiotic-resistant common clonal groups of MRSA strains in 2 different cities in this study may indicates the spread of these clonal types in north and center of Iran and highlights the common origin of such strains believed to be endemic in various sources.