A complete view of the Escherichia coli O-antigen biosynthesis gene cluster and the development of molecular-based O-serogrouping methods.

Much of what we know about Escherichia coli populations and epidemiology is defined at some level by O serogroups. Moreover, in our collective knowledge, outbreak and disease reports and elsewhere, all information of pathogenic E. coli have O serogroup records. O-serogroup diversification shows a strong association with the genetic diversity of O-antigen biosynthesis genes, and O-serogroup-specific sequences can be used as genetic markers for identifying O serogroups. We sequenced all the known O-antigen biosynthesis gene clusters (O-AGCs) from the 184 E. coli defined O serogroups and determined their genetic makeup and diversity. Subsequently, based on a highly detailed analysis of O-AGCs, we developed comprehensive and practical molecular O-serogrouping platforms; PCR-based "E. coli O-genotuping PCR" and in silico-based "SerotypeFinder". These simple and exhaustive systems may integrate microbial typing, genomics and evolutionary analyses.