Phylogenetic Clades 6 and 8 of Enterohemorrhagic Escherichia coli O157:H7 With Particular stx Subtypes are More Frequently Found in Isolates From Hemolytic Uremic Syndrome Patients Than From Asymptomatic Carriers

Iyoda, Sunao; Manning, Shannon D.; Seto, Kazuko; Kimata, Keiko; Isobe, Junko; Etoh, Yoshiki; Ichihara, Sachiko; Migita, Yuji; Ogata, Kikuyo; Honda, Mikiko; Kubota, Tsutomu; Kawano, Keiichi; Matsumoto, Kin’ya; Kudaka, Jun; Asai, Norio; Yabata, Junko; Tominaga, Kiyoshi; Terajima, Jun; Morita-Ishihara, Tomoko; Izumiya, Hidemasa; Ogura, Yoshitoshi; Saitoh, Takehito; Iguchi, Atsushi; Kobayashi, Hideki; Hara-Kudo, Yukiko; Ohnishi, Makoto; Arai, Reiko; Kawase, Masao; Asano, Yukiko; Asoshima, Nanami; Chiba, Kazuki; Furukawa, Ichiro; Kuroki, Toshiro; Hamada, Masanori; Harada, Seiya; Hatakeyama, Takashi; Hirochi, Takashi; Sakamoto, Yumiko; Hiroi, Midori; Kanda, Takashi; Horikawa, Kazumi; Iwabuchi, Kaori; Kameyama, Mitsuhiro; Kasahara, Hitomi; Kawanishi, Shinya; Kikuchi, Koji; Ueno, Hiroyuki; Kitahashi, Tomoko; Kojima, Yasuo; Konishi, Noriko; Obata, Hiromi; Kai, Akemi; Kono, Tomomi; Kurazono, Takayuki; Matsumoto, M.; Matsumoto, Yuko; Nagai, Yuhki; Naitoh, Hideki; Nakajima, Hiroshi; Nakamura, Hiromi; Nakane, Koji; Nishi, Keiko; Saitoh, Etsuko; Satoh, Hiroaki; Takamura, Mitsuteru; Shiraki, Yutaka; Tanabe, Junichi; Tanaka, Keiko; Tokoi, Yuki; Yatsuyanagi, Jun

doi:10.1093/ofid/ofu061

Cited by 51 publications

(68 citation statements)

References 34 publications

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“…The strains clustering within clade 8 demonstrate increased virulence potential (19), as patients presenting HUS symptoms were more likely to be infected with strains from this group. A larger study confirmed this observation, noting that clade 6 and clade 8 strains were more frequently associated with HUS than were strains from other clades (23).…”

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confidence: 58%

“…Studies on Stx2 expression showed that human clinical isolates belonging to lineage I or I/II produce higher Stx2 levels than cattle-derived lineage II isolates (17,20). Further classifying the strains based on SNP typing identified a subset called clade 8, which is associated with higher incidence of HUS than other clades (19,23). An example of a large outbreak caused by a clade 8 strain is the multistate spinach outbreak in 2006, with 205 cases and 3 casualties reported (36).…”

Section: Discussionmentioning

confidence: 99%

“…Given the dramatic in vitro and in vivo data related to strain PA2; the known link between Stx2a and development of severe outcomes, such as HUS (2, 3); and reports that strains of clade 8 are particularly virulent (19,23), we tested whether the Stx2a amplification could be generalized to other clade 8 strains. We included strains that produce Stx2a only and strains that produce both Stx2a and Stx2c, as these are the two toxin genotypes most correlated with HUS development (23).…”

Section: Discussionmentioning

confidence: 99%

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Coculture of Escherichia coli O157:H7 with a Nonpathogenic E. coli Strain Increases Toxin Production and Virulence in a Germfree Mouse Model

et al. 2015

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c Escherichia coli O157:H7 is a notorious foodborne pathogen due to its low infectious dose and the disease symptoms it causes, which include bloody diarrhea and severe abdominal cramps. In some cases, the disease progresses to hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS), due to the expression of one or more Shiga toxins (Stx). Isoforms of Stx, including Stx2a, are encoded within temperate prophages. In the presence of certain antibiotics, phage induction occurs, which also increases the expression of toxin genes. Additionally, increased Stx2 accumulation has been reported when O157:H7 was cocultured with phage-susceptible nonpathogenic E. coli. This study characterized an E. coli O157:H7 strain, designated PA2, that belongs to the hypervirulent clade 8 cluster. Stx2a levels after ciprofloxacin induction were lower for PA2 than for the prototypical outbreak strains Sakai and EDL933. However, during coculture with the nonpathogenic strain E. coli C600, PA2 produced Stx2a levels that were 2-to 12-fold higher than those observed during coculture with EDL933 and Sakai, respectively. Germfree mice cocolonized by PA2 and C600 showed greater kidney damage, increased Stx2a accumulation in feces, and more visible signs of disease than mice given PA2 or C600 alone. These data suggest one mechanism by which microorganisms associated with the colonic microbiota could enhance the virulence of E. coli O157:H7, particularly a subset of clade 8 strains.E scherichia coli can be either nonpathogenic, as exemplified by the bacteria associated with the normal human gut microflora, or pathogenic, classified as intestinal or extraintestinal (1). The intestinal pathogenic E. coli group is further subdivided into six pathotypes, among which enterohemorrhagic E. coli (EHEC) is a causative agent of bloody diarrhea, hemorrhagic colitis (HC), and hemolytic uremic syndrome (HUS). Shiga toxins (Stx) are one of the defining virulence factors of E. coli O157:H7 (2, 3). The stx genes are carried within lambdoid prophages downstream of the promoter for late gene expression. The toxin is released after phage-induced lysis of the bacterial cell (4). Shiga toxins are approximately 70-kDa proteins, consisting of an enzymatically active A subunit and a pentameric B subunit. The A subunit is an N-glycosidase and inactivates the 60S ribosomal subunit. This leads to inhibition of protein synthesis in the eukaryotic cell (5). There are two antigenically distinct Stx proteins, designated Stx1 and Stx2 (6). Despite having an amino acid identity of 57%, mouse and primate studies have shown that Stx2 causes more severe disease outcomes than Stx1 (7, 8). Several allelic variants of Stx2 have been described, based on the amino acid differences in the A and B subunits. The most common forms of Stx2 expressed by E. coli O157:H7 human isolates are Stx2a and Stx2c (9, 10).Since its first report in 1983 (11), the serotype O157:H7 rapidly became a notorious foodborne pathogen due to its severe disease outcomes and an infectious dose of less than 100...

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confidence: 58%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Coculture of Escherichia coli O157:H7 with a Nonpathogenic E. coli Strain Increases Toxin Production and Virulence in a Germfree Mouse Model

et al. 2015

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“…For example, human isolates are more commonly classified as lineage I and I/II than lineage II, 7,8 and it has been argued that isolates from clades 6 and 8 are more virulent than isolates from other clades. 6,9,10 Many virulence factors contribute to the pathogenesis of E. coli O157:H7 including Stx. 11,12 This is an AB 5 toxin, comprised of a single A subunit associated with 5 identical B subunits.…”

Section: Introductionmentioning

confidence: 99%

A Quantitative Enzyme-Linked Immunosorbent Assay for Shiga Toxin 2a Requiring Only Commercially Available Reagents

Xiaoli¹,

Dudley²

2017

Adv Food Technol Nutr Sci Open J

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CitationThis study develops a quantitative ELISA for measuring Shiga toxin 2 (Stx2) produced by Shiga toxin (Stx)-producing Escherichia coli (STEC), including foodborne pathogen E. coli O157:H7 by all commercially available reagents. Background: Most foodborne outbreak strains of STEC produce Stx2a, Stx2c or both, which are more frequently associated with human clinical cases, leading to severe gastrointestinal diseases or even death. However, no simple and cheap assays or kits are available for quantitative detection of Stx2a and Stx2c. Therefore, an easy and affordable quantitative method for Stx2 is needed for its pathogenesis study. Results: We successfully developed a sensitive and specific receptor-based ELISA by using all commercial available agents. Hydroxyl acyl ceramide trihexoside, an analogue of Stx2 receptor globotriaosylceramide (Gb3), was used for antigen capture, and several critical steps were identified that must be adhered to ensure repeatability. No cross reactivity was observed with Stx1, and linear curves could be constructed using either purified Stx2a or a bacterial lysate from an Stx2a-producing E. coli O157:H7 strain. We applied this method to quantify Stx2 production by a collection of E. coli O157:H7 strains, indicating it can be extended to qualitatively evaluate Stx2c, and providing evidence that toxin production does not necessarily correlate with strain phylogeny. Conclusion: Our R-ELISA provides a reliable way to quantify Stx2a using commercially available components, and it can also be used for detecting Stx2c. This cost-effective ELISA can be easily performed, suggesting it will be a useful tool for studying pathogenesis of STEC.

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“…1 This serotype has been frequently reported as a cause of diarrhea and HUS and therefore is the most investigated serotype worldwide. 2 A brief search shows numerous reports of O157 E. coli in Iran among isolates from different animal species and occasionally humans-albeit not associated with severe cases. For instance, O157 E. coli has been reported in humans (uncomplicated diarrhea), sheep, goats, cattle, water buffalos and camels in Iran in recent years.…”

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confidence: 99%

Escherichia coli O157:H7 in Iran: Time to Look Closer

Badouei¹

2016

Int J Enteric Pathog

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Phylogenetic Clades 6 and 8 of Enterohemorrhagic Escherichia coli O157:H7 With Particular stx Subtypes are More Frequently Found in Isolates From Hemolytic Uremic Syndrome Patients Than From Asymptomatic Carriers

Abstract: EHEC O157:H7 clade 6 strains harboring stx2a and/or stx2c and clade 8 strains harboring stx2a or stx2a/stx2c were frequently associated with childhood HUS cases in Japan. Rapid and specific detection of such lineages are required for infection control measures.

Cited by 51 publications

References 34 publications

Coculture of Escherichia coli O157:H7 with a Nonpathogenic E. coli Strain Increases Toxin Production and Virulence in a Germfree Mouse Model

Coculture of Escherichia coli O157:H7 with a Nonpathogenic E. coli Strain Increases Toxin Production and Virulence in a Germfree Mouse Model

A Quantitative Enzyme-Linked Immunosorbent Assay for Shiga Toxin 2a Requiring Only Commercially Available Reagents

Escherichia coli O157:H7 in Iran: Time to Look Closer

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