Genetic Diversity Analysis of Mupirocin-Resistant Clinical Isolates in Tehran Hospitals, Iran.

Few studies describe the molecular characterization of mupirocin resistance in strains. In this study, we evaluated the characteristics of mupirocin resistance in isolates for 1-year period in Tehran, Iran. In a cross-sectional study, we collected 51 unique mupirocin-resistant strains obtained from 648 isolates. High- and low-level resistance were determined by minimum inhibitory concentration with broth microdilution method. Presence of the genes for resistance to antibiotics and toxins was detected by polymerase chain reaction assays. Genotyping was performed by protein A () and staphylococcal cassette chromosome mec (SCC) typing, whereas clones were determined by multilocus sequence typing. Among mupirocin-resistant isolates, methicillin-resistant (MRSA) 23 (45.1%) and 28 (54.9%) isolates were classified as high- and low-level mupirocin resistance, respectively. Among the 51 tested strains 25 (49%) isolates were positive for genes. Seven different clones were detected in this study. High-level mupirocin-resistant (HLMUPR) strains belonged to ST8-SCC IV/t064 ( = 10, 19.6%), ST5-SCC IV/t002 ( = 5, 9.8%), ST8-SCC IV/t008 ( = 4, 7.8%), and ST239-SCC III/t631 ( = 4, 7.8%) clones, while low-level mupirocin-resistant (LLMUPR) strains belonged to ST22-SCC IV/t790 ( = 11, 21.6%), ST239-SCC III/t860 ( = 9, 17.7%), and ST15-SCC IV/t084 ( = 8, 15.7%) clones. Two strains belonged to ST22-SCC IV/t790 clone, despite carrying gene, and demonstrated LLMUPR phenotype. One ST8-SCCIV/t008 strain with HLMUPR was confirmed as Vancomycin-intermediate strain. Our data demonstrated the need for thorough epidemiological monitoring and a routine mupirocin testing program to prevent and detect mupirocin resistance in MRSA.