Characteristics of Methicillin-resistant Carrying the Toxic Shock Syndrome Toxin Gene: High Prevalence of Clonal Complex 22 Strains and the Emergence of New Types T223 and T605 in Iran

Methicillin-resistant (MRSA) strains that carry the gene are disseminated worldwide with varying regional incidences and different genetic backgrounds. The data on molecular characteristics of these strains is insufficient in Iran. The present study aimed to assess the characteristics and distribution of types of -positive MRSA strains. We investigated 89 MRSA isolates carrying the gene with typing, resistance gene detection and antimicrobial susceptibility. Of the 89 tested isolates, 61 (68.5%) were confirmed as multidrug resistant (MDR). The isolates were distributed across seven clonal complexes (CCs) including CC22 (42.7%), CC8 (28.1%), CC5 (11.2%), CC59 (5.6%), CC30 (4.5%), CC80 (4.5%) and CC15 (3.4%). typing identified 11 distinct types, with t223 (16.9%) and t790 (15.7%) being the most prevalent. All high-level mupirocin-resistant strains belonged to t002 ( = 8) and low-level mupirocin-resistant strains belonged to t790 ( = 6) types. Fusidic-acid-resistant isolates belonged to t437 ( = 3). iMLS phenotype was observed in t005 (6.7%), t002 (5.6%), t790 (3.4%), and t030, t044 and t084 (each 2.2%). It was found that in the -carrying MRSA strains, there were genetic diversities with a majority of the t223 type. Indeed, there is a necessity for more constructive surveillance/infection control strategies to address the prevalence and prevention of the emerging types.