Shiga Toxin–producing Escherichia coli Strains Negative for Locus of Enterocyte Effacement

Newton, Hayley J; Sloan, Joan; Bulach, Dieter; Seemann, Torsten; Allison, Cody; Tauschek, Marija; Robins-Browne, Roy M.; Paton, James C.; Whittam, Thomas S.; Paton, Adrienne W.; Hartland, Elizabeth L.

doi:10.3201/eid1502.080631

Cited by 83 publications

(93 citation statements)

References 38 publications

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“…Large hemolysin-encoding plasmids are found in the majority of STEC isolates, including those not belonging to the O157 serogroup (133). For example, STEC strains belonging to the O113 serogroup can cause sporadic cases of disease that are indistinguishable from some O157-caused diseases.…”

Section: Ehec and Stec Virulence Plasmidsmentioning

confidence: 99%

“…For example, STEC strains belonging to the O113 serogroup can cause sporadic cases of disease that are indistinguishable from some O157-caused diseases. A study by Newton et al compared the completed sequence of pO113, an STEC plasmid, to plasmids of O157 isolates (133). Between the two plasmid types, genes shared included the ehx (hly) hemolysin operon, espP, and iha (133).…”

Section: Ehec and Stec Virulence Plasmidsmentioning

confidence: 99%

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Pathogenomics of the Virulence Plasmids ofEscherichia coli

Johnson

Nolan

2009

Microbiol Mol Biol Rev

365

369

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SUMMARY Bacterial plasmids are self-replicating, extrachromosomal elements that are key agents of change in microbial populations. They promote the dissemination of a variety of traits, including virulence, enhanced fitness, resistance to antimicrobial agents, and metabolism of rare substances. Escherichia coli, perhaps the most studied of microorganisms, has been found to possess a variety of plasmid types. Included among these are plasmids associated with virulence. Several types of E. coli virulence plasmids exist, including those essential for the virulence of enterotoxigenic E. coli, enteroinvasive E. coli, enteropathogenic E. coli, enterohemorrhagic E. coli, enteroaggregative E. coli, and extraintestinal pathogenic E. coli. Despite their diversity, these plasmids belong to a few plasmid backbones that present themselves in a conserved and syntenic manner. Thanks to some recent research, including sequence analysis of several representative plasmid genomes and molecular pathogenesis studies, the evolution of these virulence plasmids and the implications of their acquisition by E. coli are now better understood and appreciated. Here, work involving each of the E. coli virulence plasmid types is summarized, with the available plasmid genomic sequences for several E. coli pathotypes being compared in an effort to understand the evolution of these plasmid types and define their core and accessory components.

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Section: Ehec and Stec Virulence Plasmidsmentioning

confidence: 99%

Section: Ehec and Stec Virulence Plasmidsmentioning

confidence: 99%

Pathogenomics of the Virulence Plasmids ofEscherichia coli

Johnson

Nolan

2009

Microbiol Mol Biol Rev

365

369

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“…A total of 11 samples (15%), 24 samples (33%), 30 samples (41%), and 8 samples (11%) were categorized in PT groups I, II, III, and IV, respectively. However, based on the pres-ence of the additional virulence factor bfpA and on screening of VF in the cultured isolates, a total of 5 samples (7%) were recategorized from PT group II to PT group III; 4 STEC isolates (O91: NM, O117:H7, O128:H2, and ONT:H31) did not contain the escV gene, and there was no correlation in the C T value of one sample for stx (39) and the other VF escV (19) and bfpA (18). The final risk categorizations were 11 samples (15%), 19 samples (26%), 35 samples (48%), and 8 samples (11%) for PT groups I, II, III, and IV, respectively ( Table 2).…”

Section: Resultsmentioning

confidence: 99%

“…These strains usually carry the LEE, a pathogenicity island (PAI) containing genes responsible for the characteristic attaching and effacing (A/E) lesions (4,13). In addition, they can be characterized by non-LEE-encoded effector (nle) genes, which are harbored on other PAIs in the bacterial chromosome (5,14,15), and virulence plasmids encoding EHEC-hemolysin (EHEC-hlyA) that are widely distributed among EHEC of different serotypes (16)(17)(18). Enteroaggregative E. coli (EAEC)-STEC hybrid strains of serotypes other than O104:H4, such as O111:H2, O86:NM, O59:NM, and Orough:NM, have also been associated with sporadic cases and outbreaks of HUS and (bloody) diarrhea, advocating the incorporation of EAEC virulence markers for the categorization of STEC (19)(20)(21).…”

mentioning

confidence: 99%

Assessing the Public Health Risk of Shiga Toxin-Producing Escherichia coli by Use of a Rapid Diagnostic Screening Algorithm

et al. 2015

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dShiga toxin-producing Escherichia coli (STEC) is an enteropathogen of public health concern because of its ability to cause serious illness and outbreaks. In this prospective study, a diagnostic screening algorithm to categorize STEC infections into risk groups was evaluated. The algorithm consists of prescreening stool specimens with real-time PCR (qPCR) for the presence of stx genes. The qPCR-positive stool samples were cultured in enrichment broth and again screened for stx genes and additional virulence factors (escV, aggR, aat, bfpA) and O serogroups (O26, O103, O104, O111, O121, O145, O157). Also, PCR-guided culture was performed with sorbitol MacConkey agar (SMAC) and CHROMagar STEC medium. The presence of virulence factors and O serogroups was used for presumptive pathotype (PT) categorization in four PT groups. The potential risk for severe disease was categorized from high risk for PT group I to low risk for PT group III, whereas PT group IV consists of unconfirmed stx qPCRpositive samples. In total, 5,022 stool samples of patients with gastrointestinal symptoms were included. The qPCR detected stx genes in 1.8% of samples. Extensive screening for virulence factors and O serogroups was performed on 73 samples. After enrichment, the presence of stx genes was confirmed in 65 samples (89%). By culture on selective media, STEC was isolated in 36% (26/73 samples). Threshold cycle (C T ) values for stx genes were significantly lower after enrichment compared to direct qPCR (P < 0.001). In total, 11 (15%), 19 (26%), 35 (48%), and 8 (11%) samples were categorized into PT groups I, II, III, and IV, respectively. Several virulence factors (stx 2 , stx 2a , stx 2f , toxB, eae, efa1, cif, espA, tccP, espP, nleA and/or nleB, tir cluster) were associated with PT groups I and II, while others (stx 1 , eaaA, mch cluster, ireA) were associated with PT group III. Furthermore, the number of virulence factors differed between PT groups (analysis of variance, P < 0.0001). In conclusion, a diagnostic algorithm enables fast discrimination of STEC infections associated with a high to moderate risk for severe disease (PT groups I and II) from less-virulent STEC (PT group III). Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen frequently identified as causative agent of acute diarrheal disease in humans. The outcomes of STEC infections may range from asymptomatic carriage and mild diarrhea to severe disease, such as hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS) (1-3).Based on pathogenic properties, a subgroup of STEC is also designated enterohemorrhagic E. coli (EHEC); this subgroup of stx-positive strains also contains the locus of enterocyte effacement (LEE) pathogenicity island (4). EHEC belongs to certain serotypes that are frequently associated with outbreaks and lifethreatening illnesses (5). Worldwide, the most common EHEC serotype both in outbreaks and in sporadic cases of severe disease is E. coli O157:H7 (4, 6, 7). Consequently, public health and regulatory responses have been focuse...

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“…Among non-O157 strains, bacteria belonging to serogroups O26, O103, O111, O121, O45, and O145 are most commonly reported from infected individuals (28). Some serogroups, notably O113, lack the LEE pathogenicity island, and compared to the LEE-positive O157 strains, relatively little is known about the factors that are important in mediating their attachment to the epithelial surface (32,33).…”

Section: Observations From Human Outbreaksmentioning

confidence: 99%

Animal Models of EnterohemorrhagicEscherichia coliInfection

Ritchie

2014

Microbiol Spectr

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The first major outbreaks caused by enterohemorrhagic Escherichia coli (EHEC) raised public and medical awareness of the risks associated with acquiring this potentially deadly infection. The widespread presence of these organisms in the environment, the severity of the clinical sequelae, and the lack of treatment options and effective preventive measures demand that we obtain a better understanding of how this group of organisms cause disease. Animal models allow study of the processes and factors that contribute to disease and, as such, form a valuable tool in the repertoire of infectious disease researchers. Yet despite more than 30 years of research, it seems that no single model host reproduces the full spectrum of clinical disease induced by EHEC in humans. In the first part of this review, a synopsis of what is known about EHEC infections is garnered from human outbreaks and biopsy specimens. The main features and limitations of EHEC infection models that are based on the three most commonly used species (pigs, rabbits, and mice) are described within a historical context. Recent advances are highlighted, and a brief overview of models based on other species is given. Finally, the impact of the host on moderating EHEC infection is considered in light of growing evidence for the need to consider the biology and virulence strategies of EHEC in the context of its niche within the intestine.

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Shiga Toxin–producing Escherichia coli Strains Negative for Locus of Enterocyte Effacement

Abstract: The ehx plasmids of these strains are highly related, which suggests acquisition of the large plasmid was central to the strains’ emergence.

Cited by 83 publications

References 38 publications

Pathogenomics of the Virulence Plasmids ofEscherichia coli

Pathogenomics of the Virulence Plasmids ofEscherichia coli

Assessing the Public Health Risk of Shiga Toxin-Producing Escherichia coli by Use of a Rapid Diagnostic Screening Algorithm

Animal Models of EnterohemorrhagicEscherichia coliInfection

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