AUTHOR=Iguchi Atsushi , Iyoda Sunao , Seto Kazuko , Nishii Hironobu , Ohnishi Makoto , Mekata Hirohisa , Ogura Yoshitoshi , Hayashi Tetsuya 

TITLE=Six Novel O Genotypes from Shiga Toxin-Producing Escherichia coli

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.00765

DOI=10.3389/fmicb.2016.00765

ISSN=1664-302X

ABSTRACT=<p>Serotyping is one of the typing techniques used to classify strains within the same species. O-serogroup diversification shows a strong association with the genetic diversity of O-antigen biosynthesis genes. In a previous study, based on the O-antigen biosynthesis gene cluster (O-AGC) sequences of 184 known <italic>Escherichia coli</italic> O serogroups (from O1 to O187), we developed a comprehensive and practical molecular O serogrouping (O genotyping) platform using a polymerase chain reaction (PCR) method, named <italic>E. coli</italic> O-genotyping PCR. Although, the validation assay using the PCR system showed that most of the tested strains were successfully classified into one of the O genotypes, it was impossible to classify 6.1% (35/575) of the strains, suggesting the presence of novel O genotypes. In this study, we conducted sequence analysis of O-AGCs from O-genotype untypeable Shiga toxin-producing <italic>E. coli</italic> (STEC) strains and identified six novel O genotypes; OgN1, OgN8, OgN9, OgN10, OgN12 and OgN31, with unique <italic>wzx</italic> and/or <italic>wzy</italic> O-antigen processing gene sequences. Additionally, to identify these novel O-genotypes, we designed specific PCR primers. A screen of O genotypes using O-genotype untypeable strains showed 13 STEC strains were classified into five novel O genotypes. The O genotyping at the molecular level of the O-AGC would aid in the characterization of <italic>E. coli</italic> isolates and will assist future studies in STEC epidemiology and phylogeny.</p>