The distribution of EDL 933 O island 122 (OI-122) was investigated in 70 strains of Verocytotoxin-producing

Closely related strains of Escherichia coli have been shown to cause extraintestinal infections in unrelated persons. This study tests whether a food reservoir may exist for these E. coli. Isolates from 3 sources over the same time period (2005–2007) and geographic area were compared. The sources comprised prospectively collected E. coli isolates from women with urinary tract infection (UTI) (n = 353); retail meat (n = 417); and restaurant/ready-to-eat foods (n = 74). E. coli were evaluated for antimicrobial drug susceptibility and O:H serotype and compared by using 4 different genotyping methods. We identified 17 clonal groups that contained E. coli isolates (n = 72) from >1 source. E. coli from retail chicken (O25:H4-ST131 and O114:H4-ST117) and honeydew melon (O2:H7-ST95) were indistinguishable from or closely related to E. coli from human UTIs. This study provides strong support for the role of food reservoirs or foodborne transmission in the dissemination of E. coli causing common community-acquired UTIs.

In the lipopolysaccharides of Escherichia coli there are five distinct core oligosaccharide (core OS) structures, designated K-12 and R1 to R4. The objective of this work was to determine the prevalences of these core OS types within the species. Unique sequences in the waa (core OS biosynthesis) gene operon were used to develop a PCR-based system that facilitated unequivocal determination of the core OS types in isolates of E. coli. This system was applied to the 72 isolates in the E. coli ECOR collection, a compilation of isolates that is considered to be broadly representative of the genetic diversity of the species. Fifty (69.4%) of the ECOR isolates contained the R1 core OS, 8 (11.1%) were representatives of R2, 8 (11.1%) were R3, 2 (2.8%) were R4, and only 4 (5.6%) were K-12. R1 is the only core OS type found in all four major phylogenetic groups (A, B1, B2, and D) in the ECOR collection. Virulent extraintestinal pathogenic E. coli isolates tend to be closely related to group B2 and, to a lesser extent, group D isolates. All of the ECOR representatives from the B2 and D groups had the R1 core OS. In contrast, commensal E. coli isolates are more closely related to group A, which contains isolates representing each of the five core OS structures. R3 was the only core OS type found in 38 verotoxigenic E. coli (VTEC) isolates from humans and cattle belonging to the common enterohemorrhagic E. coli serogroups O157, O111, and O26. Although isolates from other VTEC serogroups showed more core OS diversity, the R3 type (83.1% of all VTEC isolates) was still predominant. When non-VTEC commensal isolates from cattle were analyzed, it was found that most possessed the R1 core OS type.The lipopolysaccharides (LPSs) of Escherichia coli consist of (i) a hydrophobic lipid A component that forms the outer leaflet of the outer membrane, (ii) a phosphorylated, nonrepetitive hetero-oligosaccharide known as the core oligosaccharide (core OS), and (iii) a polysaccharide (O-PS) that extends from the cell surface and that forms the O antigen detected in serotyping (37). The smooth LPS (S-LPS) molecules found in most clinical isolates of E. coli are composed of this three-part structure, whereas rough LPS (R-LPS) lacks the O antigen and can have a truncated core OS. The extent of structural diversity in E. coli LPS molecules ranges from the highly conserved lipid A to the extreme variations reflected in more than 170 known O antigens (19). The core OS is conceptually divided into inner and outer core regions. The inner core is composed primarily of L-glycero-D-manno-heptose (heptose) and 3-deoxy-Dmanno-oct-2-ulosonic acid (Kdo) residues, and this part of the core OS is phosphorylated in E. coli. The principal features of the inner core OS structure are conserved among members of the Enterobacteriaceae, presumably reflecting its essential role in outer-membrane stability (16). The inner core OS structure carries additional (often nonstoichiometric) glycosyl substituents, but these vary according to core OS type (16,18). The outer ...

BackgroundAdherent and invasive Escherichia coli (AIEC) are commonly found in ileal lesions of Crohn's Disease (CD) patients, where they adhere to intestinal epithelial cells and invade into and survive in epithelial cells and macrophages, thereby gaining access to a typically restricted host niche. Colonization leads to strong inflammatory responses in the gut suggesting that AIEC could play a role in CD immunopathology. Despite extensive investigation, the genetic determinants accounting for the AIEC phenotype remain poorly defined. To address this, we present the complete genome sequence of an AIEC, revealing the genetic blueprint for this disease-associated E. coli pathotype.ResultsWe sequenced the complete genome of E. coli NRG857c (O83:H1), a clinical isolate of AIEC from the ileum of a Crohn's Disease patient. Our sequence data confirmed a phylogenetic linkage between AIEC and extraintestinal pathogenic E. coli causing urinary tract infections and neonatal meningitis. The comparison of the NRG857c AIEC genome with other pathogenic and commensal E. coli allowed for the identification of unique genetic features of the AIEC pathotype, including 41 genomic islands, and unique genes that are found only in strains exhibiting the adherent and invasive phenotype.ConclusionsUp to now, the virulence-like features associated with AIEC are detectable only phenotypically. AIEC genome sequence data will facilitate the identification of genetic determinants implicated in invasion and intracellular growth, as well as enable functional genomic studies of AIEC gene expression during health and disease.

Background: Genetic analysis of Escherichia coli O157:H7 strains has shown divergence into two distinct lineages, lineages I and II, that appear to have distinct ecological characteristics, with lineage I strains more commonly associated with human disease. In this study, microarray-based comparative genomic hybridization (CGH) was used to identify genomic differences among 31 E. coli O157:H7 strains that belong to various phage types (PTs) and different lineage-specific polymorphism assay (LSPA) types.