<i>Fim</i>operon variation in the emergence of Enterohemorrhagic<i>Escherichia coli</i>: an evolutionary and functional analysis

Shaikh, Nurmohammad; Holt, Nicholas J.; Johnson, James R.; Tarr, Phillip I.

doi:10.1111/j.1574-6968.2007.00781.x

Cited by 30 publications

(33 citation statements)

References 27 publications

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“…The second model maintained the overall stepwise progression of the first model, but some groups were condensed and others expanded (42,64,65). Specifically, all O55:H7 strains were placed into subgroup A, all O157:H Ϫ strains into subgroup B, and most O157:H7 isolates into "human" subgroup C, which was further subdivided into clusters 1, 2, and 3 ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Subsequent analyses proposed and refined a stepwise evolutionary model for the emergence of O157:H7 from O55:H7 based on multilocus enzyme electrophoresis typing, as well as phenotypic and genetic analysis of existing isolates of both serotypes (18,20,42,72). This stepwise model included the following: acquisition of Shiga toxin-encoding stx genes (18,65), a well-characterized virulence factor for EHEC; phenotypic markers, such as loss of the ability to ferment sorbitol (SOR) or loss of ␤-glucuronidase (GUD) activity; and nucleotide changes in the uidA (or gusA) (encodes GUD) and fimA and fimH fimbrial genes (17,50,64). Meanwhile, analysis by multilocus sequence typing (MLST) confirmed a hypothesis of parallel evolution of both EPEC and EHEC within related serogroups via multiple acquisitions of the locus of enterocyte effacement (LEE), the large virulence plasmids EAF and pO157, respectively, and stx-containing lambda-like bacteriophages in the case of EHEC (60,69,73).…”

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confidence: 99%

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Escherichia coli Serotype O55:H7 Diversity Supports Parallel Acquisition of Bacteriophage at Shiga Toxin Phage Insertion Sites during Evolution of the O157:H7 Lineage

Kyle

Cummings²,

Parker

et al. 2012

J Bacteriol

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bEnteropathogenic Escherichia coli (EPEC) continues to be a leading cause of mortality and morbidity in children around the world. Two EPEC genomes have been fully sequenced: those of EPEC O127:H6 strain E2348/69 (United Kingdom, 1969) and EPEC O55:H7 strain CB9615 (Germany, 2003). The O55:H7 serotype is a recent precursor to the virulent enterohemorrhagic E. coli O157:H7. To explore the diversity of O55:H7 and better understand the clonal evolution of O157:H7, we fully sequenced EPEC O55:H7 strain RM12579 (California, 1974), which was collected 1 year before the first U.S. isolate of O157:H7 was identified in California. Phage-related sequences accounted for nearly all differences between the two O55:H7 strains. Additionally, O55:H7 and O157:H7 strains were tested for the presence and insertion sites of Shiga toxin gene (stx)-containing bacteriophages. Analysis of non-phage-associated genes supported core elements of previous O157:H7 stepwise evolutionary models, whereas phage composition and insertion analyses suggested a key refinement. Specifically, the placement and presence of lambda-like bacteriophages (including those containing stx) should not be considered stable evolutionary markers or be required in placing O55:H7 and O157:H7 strains within the stepwise evolutionary models. Additionally, we suggest that a 10.9-kb region (block 172) previously believed unique to O55:H7 strains can be used to identify early O157:H7 strains. Finally, we defined two subsets of O55:H7 strains that share an as-yet-unobserved or extinct common ancestor with O157:H7 strains. Exploration of O55:H7 diversity improved our understanding of the evolution of E. coli O157:H7 and suggested a key revision to accommodate existing and future configurations of stx-containing bacteriophages into current models.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Escherichia coli Serotype O55:H7 Diversity Supports Parallel Acquisition of Bacteriophage at Shiga Toxin Phage Insertion Sites during Evolution of the O157:H7 Lineage

Kyle

Cummings²,

Parker

et al. 2012

J Bacteriol

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“…Also, the common O157 ancestor to subgroups B and C has never been found, and is probably extinct. Longlived O157:H7 clusters arise rarely, despite the ubiquity and flux of prophages that could conceivably spawn new groups (7,11). Cluster 2 where strains are recovered much less frequently from humans than are isolates from clusters 1 or 3 (15), might also be heading toward extinction.…”

Section: Discussionmentioning

confidence: 99%

A precise reconstruction of the emergence and constrained radiations of Escherichia coli O157 portrayed by backbone concatenomic analysis

Leopold

Magrini

Holt

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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150

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Single nucleotide polymorphisms (SNPs) in stable genome regions provide durable measurements of species evolution. We systematically identified each SNP in concatenations of all backbone ORFs in 7 newly or previously sequenced evolutionarily instructive pathogenic Escherichia coli O157:H7, O157:H ؊ , and O55:H7. The 1,113 synonymous SNPs demonstrate emergence of the largest cluster of this pathogen only in the last millennium. Unexpectedly, shared SNPs within circumscribed clusters of organisms suggest severely restricted survival and limited effective population sizes of pathogenic O157:H7, tenuous survival of these organisms in nature, source-sink evolutionary dynamics, or, possibly, a limited number of mutations that confer selective advantage. A single large segment spanning the rfb-gnd gene cluster is the only backbone region convincingly acquired by recombination as O157 emerged from O55. This concatenomic analysis also supports using SNPs to differentiate closely related pathogens for infection control and forensic purposes. However, constrained radiations raise the possibility of making false associations between isolates.E. coli ͉ evolution ͉ SNPs

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“…Of these 14 putative fimbriae, several had already been described under other names, including LpfA1 (42), LpfA2 (43), F9 (20), type 1 fimbriae (32) (34), and curli fimbriae (30). Long polar fimbria (Lpf)-encoding genes had also been described previously, including lpfA O26 and lpfA O113 , described by Toma et al (41) and Doughty et al (12), respectively.…”

Section: Enteropathogenic (Epec) and Enterohemorrhagic (Ehec)mentioning

confidence: 99%

Putative Adhesins of Enteropathogenic and EnterohemorrhagicEscherichia coliof Serogroup O26 Isolated from Humans and Cattle

2009

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Enterohemorrhagic Escherichia coli (EHEC) strains are responsible for food poisoning in developed countries via consumption of vegetal and animal food sources contaminated by ruminant feces, and some strains (O26, O111, and O118 serogroups) are also responsible for diarrhea in young calves. The prevalence of 27 putative adhesins of EHEC and of bovine necrotoxigenic E. coli (NTEC) was studied with a collection of 43 bovine and 29 human enteropathogenic (EPEC) and EHEC strains and 5 non-EPEC/non-EHEC (1 bovine and 4 human) O26 strains, using specific PCRs. Four "groups" of adhesins exist, including adhesins present in all O26 strains, adhesins present in most O26 strains, adhesins present in a few O26 strains, and adhesins not present in O26 strains. The common profile of EHEC/EPEC strains was characterized by the presence of loc3, loc5, loc7, loc11, loc14, paa, efa1, iha, lpfA O26 , and lpfA O113 genes and the absence of loc1, loc2, loc6, loc12, loc13, saa, and eibG genes. Except for the lpfA O26 gene, which was marginally associated with bovine EHEC/EPEC strains in comparison with human strains (P ‫؍‬ 0.012), none of the results significantly differentiated bovine strains from human strains. One adhesin gene (ldaE) was statistically (P < 0.01) associated with O26 EHEC/EPEC strains isolated from diarrheic calves in comparison with strains isolated from healthy calves. ldaE-positive strains could therefore represent a subgroup possessing the specific property of producing diarrhea in young calves. This is the first time that the distribution of putative adhesins has been described for such a large collection of EHEC/EPEC O26 strains isolated from both humans and cattle.

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Fimoperon variation in the emergence of EnterohemorrhagicEscherichia coli: an evolutionary and functional analysis

Cited by 30 publications

References 27 publications

Escherichia coli Serotype O55:H7 Diversity Supports Parallel Acquisition of Bacteriophage at Shiga Toxin Phage Insertion Sites during Evolution of the O157:H7 Lineage

Escherichia coli Serotype O55:H7 Diversity Supports Parallel Acquisition of Bacteriophage at Shiga Toxin Phage Insertion Sites during Evolution of the O157:H7 Lineage

A precise reconstruction of the emergence and constrained radiations of Escherichia coli O157 portrayed by backbone concatenomic analysis

Putative Adhesins of Enteropathogenic and EnterohemorrhagicEscherichia coliof Serogroup O26 Isolated from Humans and Cattle

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