scholarly journals Recycling of Shiga Toxin 2 Genes in Sorbitol-Fermenting Enterohemorrhagic Escherichia coli O157:NM

2007 ◽  
Vol 74 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Alexander Mellmann ◽  
Shan Lu ◽  
Helge Karch ◽  
Jian-guo Xu ◽  
Dag Harmsen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Integration Site ◽  
Hot Spot ◽  
Blot Hybridization ◽  
Enterohemorrhagic Escherichia Coli ◽  
Biologically Active ◽  
E Coli ◽  
Shiga Toxin 2

ABSTRACT Using colony blot hybridization with stx 2 and eae probes and agglutination in anti-O157 lipopolysaccharide serum, we isolated stx 2-positive and eae-positive sorbitol-fermenting (SF) enterohemorrhagic Escherichia coli (EHEC) O157:NM (nonmotile) strains from initial stool specimens and stx-negative and eae-positive SF E. coli O157:NM strains from follow-up specimens (collected 3 to 8 days later) from three children. The stx-negative isolates from each patient shared with the corresponding stx 2-positive isolates fliC H7, non-stx virulence traits, and multilocus sequence types, which indicates that they arose from the stx 2-positive strains by loss of stx 2 during infection. Analysis of the integrity of the yecE gene, a possible stx phage integration site in EHEC O157, in the consecutive stx 2-positive and stx-negative isolates demonstrated that yecE was occupied in stx 2-positive but intact in stx-negative strains. It was possible to infect and lysogenize the stx-negative E. coli O157 strains in vitro using an stx 2-harboring bacteriophage from one of the SF EHEC O157:NM isolates. The acquisition of the stx 2-containing phage resulted in the occupation of yecE and production of biologically active Shiga toxin 2. We conclude that the yecE gene in SF E. coli O157:NM is a hot spot for excision and integration of Shiga toxin 2-encoding bacteriophages. SF EHEC O157:NM strains and their stx-negative derivatives thus represent a highly dynamic system that can convert in both directions by the loss and gain of stx 2-harboring phages. The ability to recycle stx 2, a critical virulence trait, makes SF E. coli O157:NM strains ephemeral EHEC that can exist as stx-negative variants during certain phases of their life cycle.

scholarly journals Shiga Toxin Gene Loss and Transfer In Vitro and In Vivo during Enterohemorrhagic Escherichia coli O26 Infection in Humans

2007 ◽  
Vol 73 (10) ◽  
pp. 3144-3150 ◽  
Author(s):  
Martina Bielaszewska ◽  
Rita Prager ◽  
Robin Köck ◽  
Alexander Mellmann ◽  
Wenlan Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Gene Loss ◽  
Pulsed Field Gel Electrophoresis ◽  
Enterohemorrhagic Escherichia Coli ◽  
Toxin Gene ◽  
Shiga Toxins ◽  
E Coli

ABSTRACT Escherichia coli serogroup O26 consists of enterohemorrhagic E. coli (EHEC) and atypical enteropathogenic E. coli (aEPEC). The former produces Shiga toxins (Stx), major determinants of EHEC pathogenicity, encoded by bacteriophages; the latter is Stx negative. We have isolated EHEC O26 from patient stools early in illness and aEPEC O26 from stools later in illness, and vice versa. Intrapatient EHEC and aEPEC isolates had quite similar pulsed-field gel electrophoresis (PFGE) patterns, suggesting that they might have arisen by conversion between the EHEC and aEPEC pathotypes during infection. To test this hypothesis, we asked whether EHEC O26 can lose stx genes and whether aEPEC O26 can be lysogenized with Stx-encoding phages from EHEC O26 in vitro. The stx 2 loss associated with the loss of Stx2-encoding phages occurred in 10% to 14% of colonies tested. Conversely, Stx2- and, to a lesser extent, Stx1-encoding bacteriophages from EHEC O26 lysogenized aEPEC O26 isolates, converting them to EHEC strains. In the lysogens and EHEC O26 donors, Stx2-converting bacteriophages integrated in yecE or wrbA. The loss and gain of Stx-converting bacteriophages diversifies PFGE patterns; this parallels findings of similar but not identical PFGE patterns in the intrapatient EHEC and aEPEC O26 isolates. EHEC O26 and aEPEC O26 thus exist as a dynamic system whose members undergo ephemeral interconversions via loss and gain of Stx-encoding phages to yield different pathotypes. The suggested occurrence of this process in the human intestine has diagnostic, clinical, epidemiological, and evolutionary implications.

scholarly journals A Comparison of Shiga-Toxin 2 Bacteriophage from Classical Enterohemorrhagic Escherichia coli Serotypes and the German E. coli O104:H4 Outbreak Strain

PLoS ONE ◽  
2012 ◽  
Vol 7 (5) ◽  
pp. e37362 ◽  
Author(s):  
Chad R. Laing ◽  
Yongxiang Zhang ◽  
Matthew W. Gilmour ◽  
Vanessa Allen ◽  
Roger Johnson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Enterohemorrhagic Escherichia Coli ◽  
Outbreak Strain ◽  
E Coli ◽  
Shiga Toxin 2

scholarly journals Characterization of Clinical Escherichia coli Strains Producing a Novel Shiga Toxin 2 Subtype in Sweden and Denmark

2021 ◽  
Vol 9 (11) ◽  
pp. 2374
Author(s):  
Xiangning Bai ◽  
Flemming Scheutz ◽  
Henrik Mellström Dahlgren ◽  
Ingela Hedenström ◽  
Cecilia Jernberg
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Virulence Genes ◽  
Epidemiological Surveillance ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
Life Threatening ◽  
Macrolide Resistance Gene

Shiga toxin (Stx) is the key virulence factor in the Shiga Toxin-Producing Escherichia coli (STEC), which can cause diarrhea and hemorrhagic colitis with potential life-threatening complications. There are two major types of Stx: Stx1 and Stx2. Several Stx1/Stx2 subtypes have been identified in E. coli, varying in sequences, toxicity and host specificity. Here, we report a novel Stx2 subtype (designated Stx2m) from three clinical E. coli strains isolated from diarrheal patients and asymptomatic carriers in Sweden and Denmark. The Stx2m toxin was functional and exhibited cytotoxicity in vitro. The two Swedish Stx2m-producing strains belonged to the same serotype O148:H39 and Multilocus Sequencing Typing (MLST) Sequence Type (ST) 5825, while the Danish strain belonged to the O96:H19 serotype and ST99 type. Whole-genome sequencing (WGS) data analysis revealed that the three Stx2m-producing strains harbored additional virulence genes and the macrolide resistance gene mdf (A). Our findings expand the pool of Stx2 subtypes and highlight the clinical significance of emerging STEC variants. Given the clinical relevance of the Stx2m-producing strains, we propose to include Stx2m in epidemiological surveillance of STEC infections and clinical diagnosis.

scholarly journals Escherichia coli O157:H7 Strain Origin, Lineage, and Shiga Toxin 2 Expression Affect Colonization of Cattle

2009 ◽  
Vol 75 (15) ◽  
pp. 5074-5081 ◽  
Author(s):  
Ross M. S. Lowe ◽  
Danica Baines ◽  
L. Brent Selinger ◽  
James E. Thomas ◽  
Tim A. McAllister ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Escherichia Coli O157 ◽  
Human Origin ◽  
E Coli ◽  
Unknown Factor ◽  
Shiga Toxin 2 ◽  
The Impact ◽  
Dose Dependent

ABSTRACT Enterohemorrhagic Escherichia coli O157:H7 has evolved into an important human pathogen with cattle as the main reservoir. The recent discovery of E. coli O157:H7-induced pathologies in challenged cattle has suggested that previously discounted bacterial virulence factors may contribute to the colonization of cattle. The objective of the present study was to examine the impact of lineage type, cytotoxin activity, and cytotoxin expression on the amount of E. coli O157:H7 colonization of cattle tissue and cells in vitro. Using selected bovine- and human-origin strains, we determined that lineage type predicted the amount of E. coli O157:H7 strain colonization: lineage I > intermediate lineages > lineage II. All E. coli O157:H7 strain colonization was dose dependent, with threshold colonization at 103 to 105 CFU and maximum colonization at 107 CFU. We also determined that an as-yet-unknown factor of strain origin was the most dominant predictor of the amount of strain colonization in vitro. The amount of E. coli O157:H7 colonization was also influenced by strain cytotoxin activity and the inclusion of cytotoxins from lineage I or intermediate lineage strains increased colonization of a lineage II strain. There was a higher level of expression of the Shiga toxin 1 gene (stx 1) in human-origin strains than in bovine-origin strains. In addition, lineage I strains expressed higher levels of the Shiga toxin 2 gene (stx 2). The present study supports a role for strain origin, lineage type, cytotoxin activity, and stx 2 expression in modulating the amount of E. coli O157:H7 colonization of cattle.

scholarly journals Human Microbiota-Secreted Factors Inhibit Shiga Toxin Synthesis by Enterohemorrhagic Escherichia coli O157:H7

2008 ◽  
Vol 77 (2) ◽  
pp. 783-790 ◽  
Author(s):  
Thibaut de Sablet ◽  
Christophe Chassard ◽  
Annick Bernalier-Donadille ◽  
Marjolaine Vareille ◽  
Alain P. Gobert ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Factor ◽  
Shiga Toxin ◽  
Enterohemorrhagic Escherichia Coli ◽  
Lytic Cycle ◽  
E Coli ◽  
Human Microbiota ◽  
Shiga Toxin 2 ◽  
Uremic Syndrome ◽  
Serious Disease

ABSTRACT Escherichia coli O157:H7 is a food-borne pathogen causing hemorrhagic colitis and hemolytic-uremic syndrome, especially in children. The main virulence factor responsible for the more serious disease is the Shiga toxin 2 (Stx2), which is released in the gut after oral ingestion of the organism. Although it is accepted that the amount of Stx2 produced by E. coli O157:H7 in the gut is critical for the development of disease, the eukaryotic or prokaryotic gut factors that modulate Stx2 synthesis are largely unknown. In this study, we examined the influence of prokaryotic molecules released by a complex human microbiota on Stx2 synthesis by E. coli O157:H7. Stx2 synthesis was assessed after growth of E. coli O157:H7 in cecal contents of gnotobiotic rats colonized with human microbiota or in conditioned medium having supported the growth of complex human microbiota. Extracellular prokaryotic molecules produced by the commensal microbiota repress stx 2 mRNA expression and Stx2 production by inhibiting the spontaneous and induced lytic cycle mediated by RecA. These molecules, with a molecular mass of below 3 kDa, are produced in part by Bacteroides thetaiotaomicron, a predominant species of the normal human intestinal microbiota. The microbiota-induced stx 2 repression is independent of the known quorum-sensing pathways described in E. coli O157:H7 involving SdiA, QseA, QseC, or autoinducer 3. Our findings demonstrate for the first time the regulatory activity of a soluble factor produced by the complex human digestive microbiota on a bacterial virulence factor in a physiologically relevant context.

scholarly journals Transduction of Porcine Enteropathogenic Escherichia coli with a Derivative of a Shiga Toxin 2-Encoding Bacteriophage in a Porcine Ligated Ileal Loop System

2003 ◽  
Vol 69 (12) ◽  
pp. 7242-7247 ◽  
Author(s):  
István Tóth ◽  
Herbert Schmidt ◽  
Mohamed Dow ◽  
Anna Malik ◽  
Eric Oswald ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Prototype Strain ◽  
Epec Strain ◽  
Ileal Loop ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
K 12

ABSTRACT In this study, we have investigated the ability of detoxified Shiga toxin (Stx)-converting bacteriophages Φ3538 (Δstx 2::cat) (H. Schmidt et al., Appl. Environ. Microbiol. 65:3855-3861, 1999) and H-19B::Tn10d-bla (D. W. Acheson et al., Infect. Immun. 66:4496-4498, 1998) to lysogenize enteropathogenic Escherichia coli (EPEC) strains in vivo. We were able to transduce the porcine EPEC strain 1390 (O45) withΦ 3538 (Δstx 2::cat) in porcine ligated ileal loops but not the human EPEC prototype strain E2348/69 (O127). Neither strain 1390 nor strain E2348/69 was lysogenized under these in vivo conditions when E. coli K-12 containing H-19B::Tn10d-bla was used as the stx1 phage donor. The repeated success in the in vivo transduction of an Stx2-encoding phage to a porcine EPEC strain in pig loops was in contrast to failures in the in vitro trials with these and other EPEC strains. These results indicate that in vivo conditions are more effective for transduction of Stx2-encoding phages than in vitro conditions.

Shiga Toxin-Producing Escherichia coli Infections in Germany†

1997 ◽  
Vol 60 (11) ◽  
pp. 1454-1457 ◽  
Author(s):  
HELGE KARCH ◽  
HANS-IKO HUPPERTZ ◽  
JOCHEN BOCKEMÜHL ◽  
HERBERT SCHMIDT ◽  
ANDREAS SCHWARZKOPF ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Virulence Genes ◽  
Blot Hybridization ◽  
Clinical Manifestations ◽  
Microbiological Analysis ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
Stool Samples ◽  
A Prospective Study

A prospective study was carried out in collaboration with two children's hospitals in Würzburg, Germany to assess the incidence and clinical manifestations of infections due to Shiga toxin-producing Escherichia coli (STEC) in children. Between 1991 and 1995, stool samples from 2788 children with enteritis were investigated for the occurrence of STEC. STEC cultures from stools were screened using PCR with primers complementary to Shiga toxin 1(Stx1) and Shiga toxin 2 (Stx2) genes. PCR-positive samples were further subjected to colony blot hybridization and probe positive colonies were serotyped and analyzed for the presence of virulence genes. There was an increase in the incidence of STEC infections from 0.4% in 1991 to 2.8% in 1994. In 1995 the number of infections remained nearly unchanged (2.5%). Infection with STEC was associated with painful nonbloody diarrhea in most patients. Among the 35 patients in this study with stools containing STEC, only 9 (25.7%) had O157 colonies of which 3 (8.6%) were O157:H7 and 6 (17.1%) were sorbitol-fermenting O157:H−. In an additional study in 1994/l995, STEC etiology in 88 patients with HUS from Germany was confirmed in our laboratories by culture of STEC from stools, and in 20 additional HUS cases by serological analysis. Of the strains from stools of HUS patients, 78% belonged to serogroup O157. The most frequently isolated non-O157 serogroups were O26 and O111. These results demonstrate that when analyzing stools of patients with bloody diarrhea, HUS, or painful nonbloody diarrhea, the occurrence of non-O157:H7 strains should be considered when classical microbiological analysis fails to yield a standard enteric pathogen, such as Campylobacter. E. coli O157:H7, Salmonella. Shigella, or Yersinia.

scholarly journals Chromosomal Dynamism in Progeny of Outbreak-Related Sorbitol-Fermenting Enterohemorrhagic Escherichia coli O157:NM

2006 ◽  
Vol 72 (3) ◽  
pp. 1900-1909 ◽  
Author(s):  
Martina Bielaszewska ◽  
Rita Prager ◽  
Wenlan Zhang ◽  
Alexander W. Friedrich ◽  
Alexander Mellmann ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Outbreak Strain ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
Uremic Syndrome ◽  
Sporadic Cases ◽  
Different Strains ◽  
K 12

ABSTRACT Sorbitol-fermenting (SF) enterohemorrhagic Escherichia coli (EHEC) O157:NM (nonmotile) is a unique clone that causes outbreaks of hemorrhagic colitis and hemolytic-uremic syndrome. In well-defined clusters of cases, we have observed significant variability in pulsed-field gel electrophoresis (PFGE) patterns which could indicate coinfection by different strains. An analysis of randomly selected progeny colonies of an outbreak strain after subcultivation demonstrated that they displayed either the cognate PFGE outbreak pattern or one of four additional patterns and were <89% similar. These profound alterations were associated with changes in the genomic position of one of two Shiga toxin 2-encoding genes (stx 2) in the outbreak strain or with the loss of this gene. The two stx 2 alleles in the outbreak strain were identical but were flanked with phage-related sequences with only 77% sequence identity. Neither of these phages produced plaques, but one lysogenized E. coli K-12 and integrated in yecE in the lysogens and the wild-type strain. The presence of two stx 2 genes which correlated with increased production of Stx2 in vitro but not with the clinical outcome of infection was also found in 14 (21%) of 67 SF EHEC O157:NM isolates from sporadic cases of human disease. The variability of PFGE patterns for the progeny of a single colony must be considered when interpreting PFGE patterns in SF EHEC O157-associated outbreaks.

Enterohemorrhagic Escherichia coli Colony Check Assay for the Identification of Serogroups O26, O45, O103, O111, O121, O145, and O157 Colonies Isolated on Plating Media

2014 ◽  
Vol 77 (7) ◽  
pp. 1212-1218 ◽  
Author(s):  
BURTON BLAIS ◽  
MYLÈNE DESCHÊNES ◽  
GEORGE HUSZCZYNSKI ◽  
MARTINE GAUTHIER
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
High Throughput Screening ◽  
Enterohemorrhagic Escherichia Coli ◽  
Test Results ◽  
Bacterial Strains ◽  
Enrichment Broth ◽  
Substrate Solution ◽  
E Coli ◽  
Assay Performance

A simple immunoenzymatic enterohemorrhagic Escherichia coli (EHEC) colony check (ECC) assay was developed for the presumptive identification of priority EHEC colonies isolated on plating media from enrichment broth cultures of foods. With this approach, lipopolysaccharide extracted from a colony is spotted on the grid of a polymyxin-coated polyester cloth strip, and bound E. coli serogroup O26, O45, O103, O111, O121, O145, and O157 antigens are subsequently detected by sequential reactions with a pool of commercially available peroxidase-conjugated goat antibodies and tetramethylbenzidine substrate solution. Each strip can accommodate up to 15 colonies, and test results are available within 30 min. Assay performance was verified using colonies from a total of 73 target EHEC isolates covering the range of designated priority serogroups (all of which were reactive), 41 nontarget E. coli isolates including several nontarget Shiga toxin–producing E. coli serogroups (all unreactive), and 33 non–E. coli strains (all unreactive except two bacterial strains possessing O-antigenic structures in common with those of the priority EHEC). The ECC assay was reactive with target colonies grown on several types of selective and nonselective plating media designed for their cultivation. These results support the use of the ECC assay for high-throughput screening of colonies isolated on plating media for detecting priority EHEC strains in foods.

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