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 Antibody-Based Protection of Gnotobiotic Piglets Infected with Escherichia coli O157:H7 against Systemic Complications Associated with Shiga Toxin 2

1999 ◽  
Vol 67 (7) ◽  
pp. 3645-3648 ◽  
Author(s):  
Art Donohue-Rolfe ◽  
Ivanela Kondova ◽  
Jean Mukherjee ◽  
Kerry Chios ◽  
David Hutto ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Systemic Complications ◽  
E Coli ◽  
Control Serum ◽  
Shiga Toxin 2 ◽  
Uremic Syndrome ◽  
Cerebellar Lesions ◽  
Serious Disease ◽  
Gnotobiotic Piglets

ABSTRACT Hemolytic-uremic syndrome (HUS) is a serious disease in children, attributable in the majority of cases to infection with Shiga toxin (Stx)-producing Escherichia coli. Using gnotobiotic piglets orally infected with E. coli O157:H7, which develop Stx-related cerebellar lesions and fatal neurological symptoms, we show that administration of Stx2-specific antiserum well after challenge protected, in a dose-response fashion, against these symptoms for at least 24 h after bacterial challenge. Twenty-six of 30 piglets given Stx2 antiserum survived the challenge, compared to only 4 of 16 animals given control serum or saline. Given our observations in piglets, Stx antibody of human origin may likewise prevent HUS in children.

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 Cognitive deficits found in a pro-inflammatory state are independent of ERK 1/2 signaling in the murine brain hippocampus treated with Shiga toxin 2 from enterohemorrhagic Escherichia Coli

2020 ◽  
Author(s):  
Clara Berdasco ◽  
Alipio Pinto ◽  
Mariano Blake ◽  
Fernando Correa ◽  
Nadia A. Longo Carbajosa ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Central Nervous System ◽  
Nervous System ◽  
Hemolytic Uremic Syndrome ◽  
Signaling Pathway ◽  
Shiga Toxin ◽  
Enterohemorrhagic Escherichia Coli ◽  
Shiga Toxin 2 ◽  
Uremic Syndrome ◽  
The Brain

AbstractShiga toxin 2 (Stx2) from enterohemorrhagic Escherichia coli (EHEC) produces hemorrhagic colitis, hemolytic uremic syndrome (HUS) and acute encephalopathy. The mortality rate in HUS increases significantly when the central nervous system (CNS) is involved. Besides, EHEC also releases lipopolysaccharide (LPS). Many reports have described cognitive dysfunctions in HUS patients, the hippocampus being one of the brain areas targeted by EHEC infection. In this context, a translational murine model of encephalopathy was employed to establish the deleterious effects of Stx2 and the contribution of LPS in the hippocampus. Results demonstrate that systemic administration of a sublethal dose of Stx2 reduced memory index and produced depression like behavior, pro-inflammatory cytokine release and NF-kB activation independent of the ERK 1/2 signaling pathway. On the other hand, LPS activated NF-kB dependent on ERK 1/2 signaling pathway. Cotreatment of Stx2 with LPS aggravated the pathologic state, while dexamethasone treatment succeeded in preventing behavioral alterations. Our present work suggests that the use of drugs such as corticosteroids or NF-kB signaling inhibitors may serve as neuroprotectors from EHEC infection.Author SummaryShiga toxin (Stx) from enterohemorrhagic Escherichia coli (EHEC) is one of the most virulent factors responsible for hemolytic uremic syndrome (HUS). Stx2, the endemic variant targets the brain, among other organs, thus inducing encephalopathies. Central nervous system (CNS) compromise was the main predictor of death in patients with HUS. Stx2 may exert a direct action in the CNS, by disrupting the neurovascular unit. In this context, we investigate the molecular signaling triggered by Stx2 in the murine brain hippocampus involved in inflammatory mechanisms that altered hippocampal-related cognitive behaviors. The present data underscore that the use of drugs such as dexamethasone or those blocking the cascade by preventing NF-kB translocation to the nucleus may serve as effective neuroprotectors with potentially beneficial use in the clinic.

scholarly journals Nonpathogenic Escherichia coli Can Contribute to the Production of Shiga Toxin

2003 ◽  
Vol 71 (6) ◽  
pp. 3107-3115 ◽  
Author(s):  
Shantini D. Gamage ◽  
Jane E. Strasser ◽  
Claudia L. Chalk ◽  
Alison A. Weiss
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Gastrointestinal Disease ◽  
Intestinal Flora ◽  
Gene Promoter ◽  
Toxin Production ◽  
Lytic Cycle ◽  
Resistant Bacteria ◽  
E Coli ◽  
Shiga Toxin 2

ABSTRACT The food-borne pathogen, Escherichia coli O157:H7, has been associated with gastrointestinal disease and the life-threatening sequela hemolytic uremic syndrome. The genes for the virulence factor, Shiga toxin 2 (Stx2), in E. coli O157:H7 are encoded on a temperate bacteriophage under the regulation of the late gene promoter. Induction of the phage lytic cycle is required for toxin synthesis and release. We investigated the hypothesis that nonpathogenic E. coli could amplify Stx2 production if infected with the toxin-encoding phage. Toxin-encoding phage were incubated with E. coli that were either susceptible or resistant to the phage. The addition of phage to phage-susceptible bacteria resulted in up to 40-fold more toxin than a pure culture of lysogens, whereas the addition of phage to phage-resistant bacteria resulted in significantly reduced levels of toxin. Intestinal E. coli isolates incubated with Shiga toxin-encoding phage produced variable amounts of toxin. Of 37 isolates, 3 produced significantly more toxin than was present in the inoculum, and 1 fecal isolate appeared to inactivate the toxin. Toxin production in the intestine was assessed in a murine model. Fecal toxin recovery was significantly reduced when phage-resistant E. coli was present. These results suggest that the susceptibility of the intestinal flora to the Shiga toxin phage could exert either a protective or an antagonistic influence on the severity of disease by pathogens with phage-encoded Shiga toxin. Toxin production by intestinal flora may represent a novel strategy of pathogenesis.

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 Annexin Induces Cellular Uptake of Extracellular Vesicles and Delays Disease in Escherichia coli O157:H7 Infection

2021 ◽  
Vol 9 (6) ◽  
pp. 1143
Author(s):  
Ashmita Tontanahal ◽  
Ida Arvidsson ◽  
Diana Karpman
Keyword(s):  
Escherichia Coli ◽  
Extracellular Vesicles ◽  
Hela Cells ◽  
Shiga Toxin ◽  
Membrane Dynamics ◽  
Enterohemorrhagic Escherichia Coli ◽  
Raw264.7 Cells ◽  
E Coli ◽  
Uremic Syndrome ◽  
Dose Dependent

Enterohemorrhagic Escherichia coli secrete Shiga toxin and lead to hemolytic uremic syndrome. Patients have high levels of circulating prothrombotic extracellular vesicles (EVs) that expose phosphatidylserine and tissue factor and transfer Shiga toxin from the circulation into the kidney. Annexin A5 (AnxA5) binds to phosphatidylserine, affecting membrane dynamics. This study investigated the effect of anxA5 on EV uptake by human and murine phagocytes and used a mouse model of EHEC infection to study the effect of anxA5 on disease and systemic EV levels. EVs derived from human whole blood or HeLa cells were more readily taken up by THP-1 cells or RAW264.7 cells when the EVs were coated with anxA5. EVs from HeLa cells incubated with RAW264.7 cells induced phosphatidylserine exposure on the cells, suggesting a mechanism by which anxA5-coated EVs can bind to phagocytes before uptake. Mice treated with anxA5 for six days after inoculation with E. coli O157:H7 showed a dose-dependent delay in the development of clinical disease. Treated mice had lower levels of EVs in the circulation. In the presence of anxA5, EVs are taken up by phagocytes and their systemic levels are lower, and, as EVs transfer Shiga toxin to the kidney, this could postpone disease development.

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.

scholarly journals The CI Repressors of Shiga Toxin-Converting Prophages Are Involved in Coinfection of Escherichia coli Strains, Which Causes a Down Regulation in the Production of Shiga Toxin 2

2008 ◽  
Vol 190 (13) ◽  
pp. 4722-4735 ◽  
Author(s):  
R. Serra-Moreno ◽  
J. Jofre ◽  
M. Muniesa
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Antibiotic Resistance Gene ◽  
Vero Cells ◽  
Toxin Production ◽  
Lytic Cycle ◽  
Host Chromosome ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
K 12

ABSTRACT Shiga toxins (Stx) are the main virulence factors associated with a form of Escherichia coli known as Shiga toxin-producing E. coli (STEC). They are encoded in temperate lambdoid phages located on the chromosome of STEC. STEC strains can carry more than one prophage. Consequently, toxin and phage production might be influenced by the presence of more than one Stx prophage on the bacterial chromosome. To examine the effect of the number of prophages on Stx production, we produced E. coli K-12 strains carrying either one Stx2 prophage or two different Stx2 prophages. We used recombinant phages in which an antibiotic resistance gene (aph, cat, or tet) was incorporated in the middle of the Shiga toxin operon. Shiga toxin was quantified by immunoassay and by cytotoxicity assay on Vero cells (50% cytotoxic dose). When two prophages were inserted in the host chromosome, Shiga toxin production and the rate of lytic cycle activation fell. The cI repressor seems to be involved in incorporation of the second prophage. Incorporation and establishment of the lysogenic state of the two prophages, which lowers toxin production, could be regulated by the CI repressors of both prophages operating in trans. Although the sequences of the cI genes of the phages studied differed, the CI protein conformation was conserved. Results indicate that the presence of more than one prophage in the host chromosome could be regarded as a mechanism to allow genetic retention in the cell, by reducing the activation of lytic cycle and hence the pathogenicity of the strains.

scholarly journals Highly Virulent Non-O157 Enterohemorrhagic Escherichia coli (EHEC) Serotypes Reflect Similar Phylogenetic Lineages, Providing New Insights into the Evolution of EHEC

2015 ◽  
Vol 81 (20) ◽  
pp. 7041-7047 ◽  
Author(s):  
Inga Eichhorn ◽  
Katrin Heidemanns ◽  
Torsten Semmler ◽  
Bianca Kinnemann ◽  
Alexander Mellmann ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Enterohemorrhagic Escherichia Coli ◽  
Toxin Gene ◽  
Content Type ◽  
E Coli ◽  
Healthy Humans ◽  
Uremic Syndrome ◽  
Enterocyte Effacement ◽  
Phylogenetic Lineages

ABSTRACTEnterohemorrhagicEscherichia coli(EHEC) is the causative agent of bloody diarrhea and extraintestinal sequelae in humans, most importantly hemolytic-uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). Besides the bacteriophage-encoded Shiga toxin gene (stx), EHEC harbors the locus of enterocyte effacement (LEE), which confers the ability to cause attaching and effacing lesions. Currently, the vast majority of EHEC infections are caused by strains belonging to five O serogroups (the “big five”), which, in addition to O157, the most important, comprise O26, O103, O111, and O145. We hypothesize that these four non-O157 EHEC serotypes differ in their phylogenies. To test this hypothesis, we used multilocus sequence typing (MLST) to analyze a large collection of 250 isolates of these four O serogroups, which were isolated from diseased as well as healthy humans and cattle between 1952 and 2009. The majority of the EHEC isolates of O serogroups O26 and O111 clustered into one sequence type complex, STC29. Isolates of O103 clustered mainly in STC20, and most isolates of O145 were found within STC32. In addition to these EHEC strains, STC29 also includedstx-negativeE. colistrains, termed atypical enteropathogenicE. coli(aEPEC), yet another intestinal pathogenicE. coligroup. The finding that aEPEC and EHEC isolates of non-O157 O serogroups share the same phylogeny suggests an ongoing microevolutionary scenario in which the phage-encoded Shiga toxin genestxis transferred between aEPEC and EHEC. As a consequence, aEPEC strains of STC29 can be regarded as post- or pre-EHEC isolates. Therefore, STC29 incorporates phylogenetic information useful for unraveling the evolution of EHEC.

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