Prevalence and Genetic Diversity of Staphylococcal Enterotoxin (-Like) Genes sey , selw , selx , selz , sel26 and sel27 in Community-Acquired Methicillin-Resistant Staphylococcus aureus

Staphylococcal enterotoxins (SEs) are virulence factors of associated with various toxic diseases due to their emetic and superantigenic activities. Although at least 27 SE(-like) genes have been identified in to date, the newly identified SE(-like) genes have not yet been well characterized by their epidemiological features. In this study, the prevalence and genetic diversity of SE gene and SE-like genes , , , , and were investigated for 624 clinical isolates of community-acquired methicillin-resistant (CA-MRSA). The most prevalent SE(-like) gene was (92.9%), followed by (85.6%), (35.4%) and (5.6%), while and were not detected. Phylogenetically, , , , and were discriminated into 7, 10, 16, and 9 subtypes (groups), respectively. Among these subtypes, was the most conserved and showed the highest sequence identity (>98.8%), followed by and . The SE-like gene was the most divergent, and four out of ten genetic groups contained pseudogenes that may encode truncated product. Individual subtypes of SE(-like) genes were generally found in isolates with specific genotypes/lineages of . This study revealed the putative ubiquity of and and the prevalence of and in some specific lineages (e.g., ST121) in CA-MRSA, suggesting a potential role of these newly described SEs(-like) in pathogenicity.