Phenotypic and Molecular Characterization of Methicillin-Resistant Staphylococcus aureus Clones Carrying the Panton-Valentine Leukocidin Genes Disseminating in Iranian Hospitals.

The spread of Panton-Valentine leukocidin (PVL)-carrying Staphylococcus aureus strains in both hospital and the community is a significant worldwide problem. The aim of the study was to investigate the clonal dissemination pattern of PVL-producing S. aureus strains isolated from hospitalized patients in Tehran, Iran. In this cross-sectional study, 70 PVL-carrying S. aureus strains were recovered from 240 clinical specimens and characterized by antibiotic susceptibility testing, agr typing, SCC mec typing, spa typing, multilocus sequence typing, and virulence and adhesion gene profiling. All the PVL-carrying S. aureus strains were confirmed as methicillin-resistant S. aureus (MRSA) and recovered from wounds (48.6%), blood (25.7%), exudate/pus (11.4%), sputum (8.6%), and body fluid (5.7%) samples. Among the 70 PVL-carrying S. aureus strains tested, 38 (54.3%) were positive for ant (4')-Ia gene, 27 (38.6%) for aac (6')-Ie/aph (2″) , 13 (18.6%) for msr (A), 13 (18.6%) for erm (C) , 13 (18.6%) for tet (M) , 11 (15.7%) for erm (A) , 10(14.3%) for msr (B), 9 (12.9%) for aph (3')-IIIa , 5 (7.1%) for mupA , and 2 (2.9%) for erm (B) genes. Five clonal complexes (CC) and nine different clones were detected in this study. The most frequent CC was CC22 (ST22) (42.8%) followed by CC30 (ST30) (21.5%), CC8 (ST8) (17.2%), CC1 (ST772) (11.4%), and CC80 (ST80) (7.1%). In this study, ST22-SCC mec IV/t852 was the predominant PVL-positive MRSA clone (20%), followed by ST8-SCC mec IV/t008 (17.2%), ST30-SCC mec IV/t019 (12.9%), ST22-SCC mec IV/t790 (11.4%), ST22-SCC mec IV/t005 (11.4%), ST30-SCC mec IV/t021 (8.6%), ST80-SCC mec IV/t044 (7.1%), ST772-SCC mec V/t657 (7.1%), and ST772-SCC mec V/t10795 (4.3%). Diversity in clonal types of PVL-carrying MRSA strains in our study supports the need to perform a systematic surveillance of PVL-positive MRSA strains.