Genetic diversity and epidemiology of accessory gene regulator loci in .

Quorum sensing is known to regulate bacterial virulence, and the accessory gene regulator () loci is one of the genetic loci responsible for its regulation. Recent reports examining show that two loci, and regulate toxin production, but the diversity of loci and their epidemiology is unknown. In our study, analysis was performed to research genetic diversity of , and isolates from clinical samples underwent multilocus sequence typing (MLST) and PCR analysis of loci. To reveal the distribution of among different strains, phylogenetic analysis was also performed. In our analysis, two different subtypes, named and , were found in which were previously reported. PCR analysis of 133 . isolates showed that 131 strains had , 61 strains had , and 26 strains had was mainly found in clade 1 or clade 2 organisms, whereas was only found in clade 4. With rare exception, -negative sequence types (STs) belonged to clade C-Ⅰ and C-Ⅲ, and one clade 4 strain had . Our study revealed subtypes of not previously recognized, and the distribution of several loci in . These findings provide a foundation for further functional and clinical research of the loci.