Identification serologically, chemically and genetically of two Escherichia coli strains as candidates for new O serogroups

Abstract

Escherichia coli strains are normally identified by the combination of their O and H (and sometimes K) antigens, and serotyping based on the antigens is believed to be crucial for clinical detection and epidemiological investigation. Two E. coli strains, G5413 and G5287, were isolated from faecal samples of female patients with diarrhoea and were not agglutinated with any antisera that cover the well-known O serogroups of E. coli. We elucidated the Opolysaccharide (OPS) structures and analysed the O-antigen gene clusters of these bacteria. The OPS structure of G5413 established by monosaccharide analysis and NMR spectroscopy was found to be unique amongst known bacterial polysaccharide structures. The O-antigen gene cluster of this strain was sequenced and did not match sequence data with any of the 184 O serogroups that have been recognized internationally. Gene functions were tentatively assigned and were appropriate to the OPS structure. Based on these data, we suggest G5413 as a candidate for a new E. coli O serogroup. Both the OPS structure and O-antigen gene cluster of G5287 were identical to those of E. coli L-19, a candidate for another new O serogroup characterized by us recently. Recognition of these two provisional O serogroups increases the number of known O-antigen forms of E. coli to 186.

O-Antigen Gene Clusters of Plesiomonas shigelloides Serogroups and Its Application in Development of a Molecular Serotyping Scheme

“…Three distinct pathways participated in the synthesis and translocation of OPS: the Wzx/Wzy pathway, the ATP-binding cassette (ABC) transporter pathway (Hu et al, 2013), and the synthase pathway. O-antigen serotyping, targeting the wzx and wzy genes, is able to detect distinct O-antigen forms, including E. coli , Shigella , Salmonella , Vibrio parahaemolyticus , Acinetobacter , Hafnia , and Proteus (Li et al, 2009, 2010; Guo et al, 2013; Hu et al, 2013; Chen et al, 2015; Duan et al, 2016; Yu et al, 2017). Our previous studies employed wzx and wzy for serotyping E. coli and Shigella by microarray (Li et al, 2006), wzx and wzy for serotyping Pseudomonas aeruginosa (Li et al, 2018) and wzm and wzt for serotyping 15 Legionella pneumophila serogroups by microarray (Cao et al, 2013).…”

Additional Og-Typing PCR Techniques Targeting Escherichia coli-Novel and Shigella -Unique O-Antigen Biosynthesis Gene Clusters

“…Through genomic studies in recent years, numerous novel O-AGCs have been found in E. coli isolates (3,(6)(7)(8)(9)(10)(11). In Shiga toxin-producing E. coli (STEC) and enterotoxigenic E. coli (ETEC) studies, we found six (OgN1, OgN8, OgN9, OgN10, OgN12, and OgN31) and nine (OgN2, OgN3, OgN4, OgN5, OgN13, OgN14, OgN15, OgN16, and OgN17) novel O-AGCs, respectively, indicating that their wzx and wzy sequences were unique compared to those from known O-AGCs (less than 70% DNA sequence identity of closest pairs) (7,8).…”

Structural Determination and Genetic Identification of the O-Antigen from an Escherichia coli Strain, LL004, Representing a Novel Serogroup

“…Generally, the O-AGC consists of three main classes of genes: (1) nucleotide sugar precursor synthesis genes, (2) glycosyltransferase genes, and (3) O-unit translocation and polymerization genes ( wzx / wzy in the Wzx/Wzy-dependent pathway and wzm / wzt in the ABC transporter pathway) [ 6 , 7 ]. In addition to the > 180 serogroups, many O genotypes of E. coli strains have been characterized according to their O-AGCs in recent years, very likely representing novel serogroups [ 8 , 9 , 10 ], however lacking the needed chemical structural data.…”