A homolog of the O157 urease-encoding O island 48 is present in porcine O149:H10 enterotoxigenic<i>Escherichia coli</i>

Parreira, Valeria R.; Liao, Jing; Kim, Sang-Hyun; Gyles, Carlton

doi:10.1051/vetres:2008015

Cited by 5 publications

(7 citation statements)

References 36 publications

(39 reference statements)

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“…This region was similar to the urease-tellurite islands found in E. coli O157:H7 strains, EHEC O26:H11 strain 11368, and EHEC O111:H Ϫ strain 11128 (51). Previous studies have identified this island among porcine ETEC O149:K88 strains (39), and portions of this island in E. coli O157:H7 were shown to be involved in colonization to ligated pig intestine (56). Therefore, this island might be important for the colonization of UMNK88 and other K88 strains.…”

Section: Resultssupporting

confidence: 74%

Genome Sequences and Phylogenetic Analysis of K88- and F18-Positive Porcine Enterotoxigenic Escherichia coli

et al. 2012

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Porcine enterotoxigenic Escherichia coli (ETEC) continues to result in major morbidity and mortality in the swine industry via postweaning diarrhea. The key virulence factors of ETEC strains, their serotypes, and their fimbrial components have been well studied. However, most studies to date have focused on plasmid-encoded traits related to colonization and toxin production, and the chromosomal backgrounds of these strains have been largely understudied. Here, we generated the genomic sequences of K88-positive and F18-positive porcine ETEC strains and examined the phylogenetic distribution of clinical porcine ETEC strains and their plasmid-associated genetic content. The genomes of porcine ETEC strains UMNK88 and UMNF18 were both found to contain remarkable plasmid complements containing known virulence factors, potential novel virulence factors, and antimicrobial resistance-associated elements. The chromosomes of these strains also possessed several unique genomic islands containing hypothetical genes with similarity to classical virulence factors, although phage-associated genomic islands dominated the accessory genomes of these strains. Phylogenetic analysis of 78 clinical isolates associated with neonatal and porcine diarrhea revealed that a limited subset of porcine ETEC lineages exist that generally contain common toxin and fimbrial profiles, with many of the isolates belonging to the ST10, ST23, and ST169 multilocus sequencing types. These lineages were generally distinct from existing human ETEC database isolates. Overall, most porcine ETEC strains appear to have emerged from a limited subset of E. coli lineages that either have an increased propensity to carry plasmid-encoded virulence factors or have the appropriate ETEC core genome required for virulence. Diarrhea is a major cause of morbidity and mortality to young pigs, resulting in significant production losses for the swine industry (10). Enterotoxigenic Escherichia coli (ETEC) strains are the most common cause of diarrhea in young pigs, resulting in a disease known as enteric colibacillosis (10). Neonatal and postweaning pigs are most susceptible to ETEC. While neonatal ETEC diarrhea is generally well controlled by using fimbria-based vaccines, postweaning enteric colibacillosis has been more difficult to control. Porcine ETEC strains are characterized by the production of specific adhesins and enterotoxins. The adhesins most common in porcine ETEC are fimbrial adhesins K88 (also called F4), K99 (F5), 987P (F6), F41, and F18, as well as afimbrial adhesins such as AIDA-I. Porcine ETEC also produce one or more enterotoxins, including heat-labile enterotoxin (LT), heat-stable enterotoxins a and b (STa and STb), and EAST1 toxin (33). These and other described porcine ETEC virulence factors have mostly been localized to plasmids. Additionally, F18-positive porcine E. coli strains implicated in edema disease and diarrhea sometimes possess the Shiga toxin-encoding gene (stx 2e ) within their chromosomes (16).Analyses of human ETEC strains have revealed ...

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Section: Resultssupporting

confidence: 74%

Genome Sequences and Phylogenetic Analysis of K88- and F18-Positive Porcine Enterotoxigenic Escherichia coli

et al. 2012

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“…In the present study, a ureasenull mutant formed significantly fewer bacterial clusters than the wild-type EHEC O157:H7 parent strain, supporting a role for urease in virulence. Although urease is not expressed in vitro by most VTEC strains (5,6), it is likely that it is expressed in vivo, thereby contributing to bacterial survival in the intestine (6,19). This suggestion is supported by our RT-PCR data that show that ureC gene transcripts from the wild-type 86-24 strain present in pig ileal loops were detected at levels similar to those of the bacteria grown in BHIN broth static cultures in vitro (unpublished data).…”

Section: Discussionmentioning

confidence: 71%

“…Complementation of the urease-null mutant by introduction of the wild-type ure gene cluster on a plasmid failed to restore the wild-type adherence phenotype in the ligated pig ileal loops. It is possible that regulation of urease synthesis might have prevented the plasmid-encoded urease from expression in the host intestine as regulation of ure expression appears complicated by unknown trans-acting factors (9,19). On the other hand, it might be the negative effect from overexpression of urease in the complemented strain as it was also observed that the complemented mutant 86-24⌬ureC (pUDG) caused even less adherence to IPEC-J2 cells than its parent mutant (data not shown).…”

Section: Discussionmentioning

confidence: 99%

Contributions of O Island 48 to Adherence of Enterohemorrhagic Escherichia coli O157:H7 to Epithelial Cells In Vitro and in Ligated Pig Ileal Loops

Wheatcroft

Chambers

et al. 2009

Appl Environ Microbiol

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O island 48 (OI-48) ofThe OI-48 aidA gene deletion had no effect on adherence in vitro or in vivo. Deletion of the iha and ureC genes had no effect on adherence in vitro but significantly reduced the colonization of EHEC O157:H7 in the ligated pig intestine. These data suggest that Te r , Iha, and urease may contribute to EHEC O157:H7 pathogenesis by promoting adherence of the pathogen to the host intestinal epithelium.The genome of enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain EDL933 contains unique blocks of sequences called O islands (OIs), which are absent from the E. coli K12 MG1655 genome. The OIs contain 1,387 genes, some of which encode virulence factors (21), thus making these OIs pathogenicity islands (PAIs). EHEC pathogenicity is mainly determined by factors encoded in these PAIs, such as OI-148 (locus of enterocyte effacement [LEE] PAI) which causes attaching and effacing (AE) lesions, and OI-45 and OI-93, which contain lambdoid phages encoding verotoxins that are required for bloody diarrhea and the hemolytic uremic syndrome. However, only 40% of the OI genes in O157:H7 strain EDL933 have been assigned a function.OI-43 and OI-48 are duplicates, encoding tellurite resistance (Te r ) and the putative adhesin Iha and are therefore called Te r -and adherence-conferring islands (TAIs) (28). EHEC O157:H7 strain EDL933 contains both OI-43 and OI-48, while the Sakai strain contains only one of these OIs. We used PCR with OI junction primers to show that O157:H7 strain 86-24 contains only OI-48, not OI-43 (data not shown). The TAI can be divided into three functional gene clusters, one encoding urease, a second encoding Te r , and the third encoding the putative adhesins Iha and AIDA-1 (Fig. 1) (21, 28). The urease genes are similar to the genes in Klebsiella aerogenes (9) while the Te r gene cluster is similar to the genes in Serratia marcesens (28). The pattern of homology indicates that the TAI is a mosaic of functional regions that were acquired on separate occasions (1). Iha is an IrgA (iron-regulated gene A) homolog adhesin (25). Because of its presence in eae (E. coli AE)-negative verotoxigenic E. coli (VTEC) strains, it has been suggested that Iha may function as an adhesin in these organisms in place of intimin (23,25). AIDA-I, encoded by aidA, is an autotransporter membrane protein with a ␤-barrel structure, and it confers on enteropathogenic E. coli the ability to diffusely adhere to epithelial cells. The AIDA-I adhesin from OI-48 has 68% homology to the AIDA-I of enteropathogenic E. coli (20,21). However, the roles of Iha and AIDA-I-like adhesins in EHEC pathogenesis have yet to be determined.The ure gene cluster consists of three structural genes, ureA, ureB, and ureC, and four accessory genes, ureD, ureE, ureF, and ureG, required for transport and processing of urease (5, 15). Interestingly, ure genes are more frequently present in eaepositive VTEC strains (113 of 132, or 85.6%) than in eaenegative VTEC strains (4 of 70, or 5.7%) although there is no physical linkage of the ure gen...

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“…Urease genes were detected in the major EHEC groups O26, O111, and O157, as well as in sorbitolfermenting EHEC O157:NM strains, but were absent from diarrheagenic E. coli strains of several other pathogroups, including enteroaggregative E. coli, enteroinvasive E. coli, and EPEC strains (18,40). In enterotoxigenic E. coli, there is a homologue of the O157 urease-encoding OI-48 (46). These investigations indicate the virulence potential of urease in EHEC.…”

Section: Discussionmentioning

confidence: 74%

Virulence Genes and Molecular Typing of Different Groups of Escherichia coli O157 Strains in Cattle

Tóth

Schmidt

Kardos³

et al. 2009

Appl Environ Microbiol

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Characterization of an Escherichia coli O157 strain collection (n ‫؍‬ 42) derived from healthy Hungarian cattle revealed the existence of diverse pathotypes. Enteropathogenic E. coli (EPEC; eae positive) appeared to be the most frequent pathotype (n ‫؍‬ 22 strains), 11 O157 strains were typical enterohemorrhagic E. coli (EHEC; stx and eae positive), and 9 O157 strains were atypical, with none of the key stx and eae virulence genes detected. EHEC and EPEC O157 strains all carried eae-gamma, tir-gamma, tccP, and paa. Other virulence genes located on the pO157 virulence plasmid and different O islands (O island 43 [OI-43] and OI-122), as well as espJ and espM, also characterized the EPEC and EHEC O157 strains with similar frequencies. However, none of these virulence genes were detected by PCR in atypical O157 strains. Interestingly, five of nine atypical O157 strains produced cytolethal distending toxin V (CDT-V) and carried genes encoding long polar fimbriae. Macro-restriction fragment enzyme analysis (pulsed-field gel electrophoresis) revealed that these E. coli O157 strains belong to four main clusters. Multilocus sequence typing analysis revealed that five housekeeping genes were identical in EHEC and EPEC O157 strains but were different in the atypical O157 strains. These results suggest that the Hungarian bovine E. coli O157 strains represent at least two main clones: EHEC/EPEC O157:H7/NM (nonmotile) and atypical CDT-V-producing O157 strains with H antigens different from H7. The CDT-V-producing O157 strains represent a novel genogroup. The pathogenic potential of these strains remains to be elucidated.Escherichia coli O157:H7 is a food-and waterborne zoonotic pathogen with serious effects on public health. E. coli O157:H7 causes diseases in humans ranging from uncomplicated diarrhea to hemorrhagic colitis and hemolytic-uremic syndrome (HUS) (30). Typically, enterohemorrhagic E. coli (EHEC) strains express two groups of important virulence factors: one or more Shiga toxins (Stx; also called verotoxins), encoded by lambda-like bacteriophages, and a pathogenicity island called the locus of enterocyte effacement (LEE) encoding all the proteins necessary for attaching and effacing lesions of epithelial cells (41). Comparative genomic studies of E. coli O157:H7 strains revealed extensive genomic diversity related to the structures, positions, and genetic contents of bacteriophages and the variability of putative virulence genes encoding non-LEE effector proteins (29, 43).Ruminants and, in particular, healthy cattle are the major reservoir of E. coli O157:H7, although the prevalence of O157:H7 strains in cattle may vary widely, as reviewed by Caprioli et al. (12). E. coli O157:H7 has been found to persist and remain infective in the environment for a long time, e.g., for at least 6 months in water trough sediments, which may be an important environmental niche.In Hungary, infections with E. coli O157 and other Shiga toxin-producing E. coli (STEC) strains in humans in cases of "enteritidis infectiosa" have been not...

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A homolog of the O157 urease-encoding O island 48 is present in porcine O149:H10 enterotoxigenicEscherichia coli

Cited by 5 publications

References 36 publications

Genome Sequences and Phylogenetic Analysis of K88- and F18-Positive Porcine Enterotoxigenic Escherichia coli

Genome Sequences and Phylogenetic Analysis of K88- and F18-Positive Porcine Enterotoxigenic Escherichia coli

Contributions of O Island 48 to Adherence of Enterohemorrhagic Escherichia coli O157:H7 to Epithelial Cells In Vitro and in Ligated Pig Ileal Loops

Virulence Genes and Molecular Typing of Different Groups of Escherichia coli O157 Strains in Cattle

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