scholarly journals Shiga Toxin-Producing Serogroup O91 Escherichia coli Strains Isolated from Food and Environmental Samples

2017 ◽  
Vol 83 (18) ◽  
Author(s):  
Peter C. H. Feng ◽  
Sabine Delannoy ◽  
David W. Lacher ◽  
Joseph M. Bosilevac ◽  
Patrick Fach ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hemolytic Uremic Syndrome ◽  
Shiga Toxin ◽  
Severe Illness ◽  
Content Type ◽  
Virulence Potential ◽  
Short Palindromic Repeat ◽  
Uremic Syndrome ◽  
Severe Infections ◽  
Genetic Profiles

ABSTRACT Shiga toxin-producing Escherichia coli (STEC) strains of the O91:H21 serotype have caused severe infections, including hemolytic-uremic syndrome. Strains of the O91 serogroup have been isolated from food, animals, and the environment worldwide but are not well characterized. We used a microarray and other molecular assays to examine 49 serogroup O91 strains (environmental, food, and clinical strains) for their virulence potential and phylogenetic relationships. Most of the isolates were identified to be strains of the O91:H21 and O91:H14 serotypes, with a few O91:H10 strains and one O91:H9 strain being identified. None of the strains had the eae gene, which codes for the intimin adherence protein, and many did not have some of the genetic markers that are common in other STEC strains. The genetic profiles of the strains within each serotype were similar but differed greatly between strains of different serotypes. The genetic profiles of the O91:H21 strains that we tested were identical or nearly identical to those of the clinical O91:H21 strains that have caused severe diseases. Multilocus sequence typing and clustered regularly interspaced short palindromic repeat analyses showed that the O91:H21 strains clustered within the STEC 1 clonal group but the other O91 serotype strains were phylogenetically diverse. IMPORTANCE This study showed that food and environmental O91:H21 strains have similar genotypic profiles and Shiga toxin subtypes and are phylogenetically related to the O91:H21 strains that have caused hemolytic-uremic syndrome, suggesting that these strains may also have the potential to cause severe illness.

scholarly journals Association of Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) Elements with Specific Serotypes and Virulence Potential of Shiga Toxin-Producing Escherichia coli

2013 ◽  
Vol 80 (4) ◽  
pp. 1411-1420 ◽  
Author(s):  
Magaly Toro ◽  
Guojie Cao ◽  
Wenting Ju ◽  
Marc Allard ◽  
Rodolphe Barrangou ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Virulence Genes ◽  
Genetic Relatedness ◽  
Average Length ◽  
Content Type ◽  
Virulence Potential ◽  
Short Palindromic Repeat ◽  
K 12 ◽  
Potential Pathogenicity

ABSTRACTShiga toxin-producingEscherichia coli(STEC) strains (n= 194) representing 43 serotypes andE. coliK-12 were examined for clustered regularly interspaced short palindromic repeat (CRISPR) arrays to study genetic relatedness among STEC serotypes. A subset of the strains (n= 81) was further analyzed for subtype I-Ecasand virulence genes to determine a possible association of CRISPR elements with potential virulence. Four types of CRISPR arrays were identified. CRISPR1 and CRISPR2 were present in all strains tested; 1 strain also had both CRISPR3 and CRISPR4, whereas 193 strains displayed a short, combined array, CRISPR3-4. A total of 3,353 spacers were identified, representing 528 distinct spacers. The average length of a spacer was 32 bp. Approximately one-half of the spacers (54%) were unique and found mostly in strains of less common serotypes. Overall, CRISPR spacer contents correlated well with STEC serotypes, and identical arrays were shared between strains with the same H type (O26:H11, O103:H11, and O111:H11). There was no association identified between the presence of subtype I-Ecasand virulence genes, but the total number of spacers had a negative correlation with potential pathogenicity (P< 0.05). Fewer spacers were found in strains that had a greater probability of causing outbreaks and disease than in those with lower virulence potential (P< 0.05). The relationship between the CRISPR-cassystem and potential virulence needs to be determined on a broader scale, and the biological link will need to be established.

scholarly journals AB5Preassembly Is Not Required for Shiga Toxin Activity

2016 ◽  
Vol 198 (11) ◽  
pp. 1621-1630 ◽  
Author(s):  
Christine A. Pellino ◽  
Sayali S. Karve ◽  
Suman Pradhan ◽  
Alison A. Weiss
Keyword(s):  
Escherichia Coli ◽  
Enzymatic Activity ◽  
Hemolytic Uremic Syndrome ◽  
Shiga Toxin ◽  
Target Cells ◽  
Content Type ◽  
B Subunit ◽  
Uremic Syndrome ◽  
A Subunit ◽  
B Subunits

ABSTRACTShiga toxin (Stx)-producingEscherichia coli(STEC) is a major cause of foodborne illness, including the life-threatening complication hemolytic-uremic syndrome. The German outbreak in 2011 resulted in nearly 4,000 cases of infection, with 54 deaths. Two forms of Stx, Stx1 and Stx2, differ in potency, and subtype Stx2a is most commonly associated with fatal human disease. Stx is considered to be an AB5toxin. The single A (enzymatically active) subunit inhibits protein synthesis by cleaving a catalytic adenine from the eukaryotic rRNA. The B (binding) subunit forms a homopentamer and mediates cellular association and toxin internalization by binding to the glycolipid globotriaosylceramide (Gb3). Both subunits are essential for toxicity. Here we report that unlike other AB5toxin family members, Stx is produced by STEC as unassembled A and B subunits. A preformed AB5complex is not required for cellular toxicity orin vivotoxicity to mice, and toxin assembly likely occurs at the cell membrane. We demonstrate that disruption of A- and B-subunit association by use of A-subunit peptides that lack enzymatic activity can protect mice from lethal doses of toxin. Currently, no treatments have been proven to be effective for hemolytic-uremic syndrome. Our studies demonstrate that agents that interfere with A- and B-subunit assembly may have therapeutic potential. Shiga toxin (Stx) produced by pathogenicEscherichia coliis considered to be an AB5heterohexamer; however, no known mechanisms ensure AB5assembly. Stx released byE. coliis not in the AB5conformation and assembles at the receptor interface. Thus, unassembled Stx can impart toxicity. This finding shows that preventing AB5assembly is a potential treatment for Stx-associated illnesses.IMPORTANCEComplications due to Shiga toxin are frequently fatal, and at present, supportive care is the only treatment option. Furthermore, antibiotic treatment is contraindicated due to the ability of antibiotics to amplify bacterial expression of Shiga toxin. We report, contrary to prevailing assumptions, that Shiga toxin produced by STEC circulates as unassembled A and B subunits at concentrations that are lethal to mice. Similar to the case for anthrax toxin, assembly occurs on receptors expressed on the surfaces of mammalian target cells. Disruption of Shiga toxin assembly by use of A-subunit peptides that lack enzymatic activity protects mice from lethal challenge with Shiga toxin, suggesting a new approach for development of therapeutics.

scholarly journals Genetic Diversity and Virulence Potential of Shiga Toxin-Producing Escherichia coli O113:H21 Strains Isolated from Clinical, Environmental, and Food Sources

2014 ◽  
Vol 80 (15) ◽  
pp. 4757-4763 ◽  
Author(s):  
Peter C. H. Feng ◽  
Sabine Delannoy ◽  
David W. Lacher ◽  
Luis Fernando dos Santos ◽  
Lothar Beutin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Genetic Diversity ◽  
Shiga Toxin ◽  
Food Sources ◽  
Content Type ◽  
Virulence Potential ◽  
Uremic Syndrome ◽  
Enterocyte Effacement ◽  
Human Infections ◽  
Pcr Microarray

ABSTRACTShiga toxin-producingEscherichia colistrains of serotype O113:H21 have caused severe human diseases, but they are unusual in that they do not produce adherence factors coded by the locus of enterocyte effacement. Here, a PCR microarray was used to characterize 65 O113:H21 strains isolated from the environment, food, and clinical infections from various countries. In comparison to the pathogenic strains that were implicated in hemolytic-uremic syndrome in Australia, there were no clear differences between the pathogens and the environmental strains with respect to the 41 genetic markers tested. Furthermore, all of the strains carried only Shiga toxin subtypes associated with human infections, suggesting that the environmental strains have the potential to cause disease. Most of the O113:H21 strains were closely related and belonged in the same clonal group (ST-223), but CRISPR analysis showed a great degree of genetic diversity among the O113:H21 strains.

scholarly journals Serogroup-Specific Bacterial Engineered Glycoproteins as Novel Antigenic Targets for Diagnosis of Shiga Toxin-Producing-Escherichia coli-Associated Hemolytic-Uremic Syndrome

2014 ◽  
Vol 53 (2) ◽  
pp. 528-538 ◽  
Author(s):  
Luciano J. Melli ◽  
Andrés E. Ciocchini ◽  
Ana J. Caillava ◽  
Nicolás Vozza ◽  
Isabel Chinen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hemolytic Uremic Syndrome ◽  
Shiga Toxin ◽  
Diagnostic Procedures ◽  
Stool Culture ◽  
Human Infection ◽  
Healthy Children ◽  
Content Type ◽  
E Coli ◽  
Uremic Syndrome

Human infection with Shiga toxin-producingEscherichia coli(STEC) is a major cause of postdiarrheal hemolytic-uremic syndrome (HUS), a life-threatening condition characterized by hemolytic anemia, thrombocytopenia, and acute renal failure.E. coliO157:H7 is the dominant STEC serotype associated with HUS worldwide, although non-O157 STEC serogroups can cause a similar disease. The detection of anti-O157E. colilipopolysaccharide (LPS) antibodies in combination with stool culture and detection of free fecal Shiga toxin considerably improves the diagnosis of STEC infections. In the present study, we exploited a bacterial glycoengineering technology to develop recombinant glycoproteins consisting of the O157, O145, or O121 polysaccharide attached to a carrier protein as serogroup-specific antigens for the serological diagnosis of STEC-associated HUS. Our results demonstrate that using these antigens in indirect ELISAs (glyco-iELISAs), it is possible to clearly discriminate between STEC O157-, O145-, and O121-infected patients and healthy children, as well as to confirm the diagnosis in HUS patients for whom the classical diagnostic procedures failed. Interestingly, a specific IgM response was detected in almost all the analyzed samples, indicating that it is possible to detect the infection in the early stages of the disease. Additionally, in all the culture-positive HUS patients, the serotype identified by glyco-iELISAs was in accordance with the serotype of the isolated strain, indicating that these antigens are valuable not only for diagnosing HUS caused by the O157, O145, and O121 serogroups but also for serotyping and guiding the subsequent steps to confirm diagnosis.

scholarly journals A Novel Tail-Associated O91-Specific Polysaccharide Depolymerase from a Podophage Reveals Lytic Efficacy of Shiga Toxin-Producing Escherichia coli

2020 ◽  
Vol 86 (9) ◽  
Author(s):  
Yibao Chen ◽  
Xiangmin Li ◽  
Shuang Wang ◽  
Lingyu Guan ◽  
Xinxin Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hemolytic Uremic Syndrome ◽  
Proinflammatory Cytokines ◽  
Shiga Toxin ◽  
Hemorrhagic Colitis ◽  
Content Type ◽  
Increased Risk ◽  
Specific Polysaccharide ◽  
Life Threatening ◽  
Uremic Syndrome

ABSTRACT Shiga toxin-producing Escherichia coli (STEC) strains are important zoonotic foodborne pathogens, causing diarrhea, hemorrhagic colitis, and life-threatening hemolytic uremic syndrome (HUS) in humans. However, antibiotic treatment of STEC infection is associated with an increased risk of HUS. Therefore, there is an urgent need for early and effective therapeutic strategies. Here, we isolated lytic T7-like STEC phage PHB19 and identified a novel O91-specific polysaccharide depolymerase (Dep6) in the C terminus of the PHB19 tailspike protein. Dep6 exhibited strong hydrolase activity across wide ranges of pH (pH 4 to 8) and temperature (20 to 60°C) and degraded polysaccharides on the surface of STEC strain HB10. In addition, both Dep6 and PHB19 degraded biofilms formed by STEC strain HB10. In a mouse STEC infection model, delayed Dep6 treatment (3 h postinfection) resulted in only 33% survival, compared with 83% survival when mice were treated simultaneously with infection. In comparison, pretreatment with Dep6 led to 100% survival compared with that of the control group. Surprisingly, a single PHB19 treatment resulted in 100% survival in all three treatment protocols. Moreover, a significant reduction in the levels of proinflammatory cytokines was observed at 24 h postinfection in Dep6- or PHB19-treated mice. These results demonstrated that Dep6 or PHB19 might be used as a potential therapeutic agent to prevent STEC infection. IMPORTANCE Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen worldwide. The Shiga-like toxin causes diarrhea, hemorrhagic colitis, and life-threatening hemolytic uremic syndrome (HUS) in humans. Although antibiotic therapy is still used for STEC infections, this approach may increase the risk of HUS. Phages or phage-derived depolymerases have been used to treat bacterial infections in animals and humans, as in the case of the “San Diego patient” treated with a phage cocktail. Here, we showed that phage PHB19 and its O91-specific polysaccharide depolymerase Dep6 degraded STEC biofilms and stripped the lipopolysaccharide (LPS) from STEC strain HB10, which was subsequently killed by serum complement in vitro. In a mouse model, PHB19 and Dep6 protected against STEC infection and caused a significant reduction in the levels of proinflammatory cytokines. This study reports the use of an O91-specific polysaccharide depolymerase for the treatment of STEC infection in mice.

scholarly journals Genome Sequence for Shiga Toxin-Producing Escherichia coli O26:H11, Associated with a Cluster of Hemolytic-Uremic Syndrome Cases in South Africa, 2017

2017 ◽  
Vol 5 (38) ◽  
Author(s):  
Anthony M. Smith ◽  
Kalule J. Bosco ◽  
Mark P. Nicol ◽  
Jackie Kleynhans ◽  
Mignon McCulloch ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
South Africa ◽  
Hemolytic Uremic Syndrome ◽  
Genome Sequence ◽  
Foodborne Pathogens ◽  
Shiga Toxin ◽  
Sequence Data ◽  
Content Type ◽  
Genome Sequence Data ◽  
Uremic Syndrome

ABSTRACT Shiga toxin-producing Escherichia coli (STEC) strains are primarily foodborne pathogens that may cause diarrheal outbreaks and are associated with severe complications, specifically hemolytic-uremic syndrome (HUS). We report here genome sequence data for STEC O26:H11, which is associated with a cluster of cases of HUS, a rarely described syndrome in South Africa.

scholarly journals Promoter Sequence of Shiga Toxin 2 (Stx2) Is Recognized In Vivo, Leading to Production of Biologically Active Stx2

mBio ◽  
2013 ◽  
Vol 4 (5) ◽  
Author(s):  
Leticia V. Bentancor ◽  
Maria P. Mejías ◽  
Alípio Pinto ◽  
Marcos F. Bilen ◽  
Roberto Meiss ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Central Nervous System ◽  
Nervous System ◽  
Hemolytic Uremic Syndrome ◽  
Shiga Toxin ◽  
Biologically Active ◽  
Eukaryotic Cells ◽  
Content Type ◽  
Uremic Syndrome

ABSTRACTShiga toxins (Stx) are the main agent responsible for the development of hemolytic-uremic syndrome (HUS), the most severe and life-threatening systemic complication of infection with enterohemorrhagicEscherichia coli(EHEC) strains. We previously described Stx2 expression by eukaryotic cells after they were transfectedin vitrowith thestx2gene cloned into a prokaryotic plasmid (pStx2). The aim of this study was to evaluate whether mammalian cells were also able to express Stx2in vivoafter pStx2 injection. Mice were inoculated by hydrodynamics-based transfection (HBT) with pStx2. We studied the survival, percentage of polymorphonuclear leukocytes in plasma, plasma urea levels, and histology of the kidneys and the brains of mice. Mice displayed a lethal dose-related response to pStx2. Stx2 mRNA was recovered from the liver, and Stx2 cytotoxic activity was observed in plasma of mice injected with pStx2. Stx2 was detected by immunofluorescence in the brains of mice inoculated with pStx2, and markers of central nervous system (CNS) damage were observed, including increased expression of glial fibrillary acidic protein (GFAP) and fragmentation of NeuN in neurons. Moreover, anti-Stx2B-immunized mice were protected against pStx2 inoculation. Our results show that Stx2 is expressedin vivofrom the wildstx2gene, reproducing pathogenic damage induced by purified Stx2 or secondary to EHEC infection.IMPORTANCEEnterohemorrhagic Shiga toxin (Stx)-producingEscherichia coli(EHEC) infections are a serious public health problem, and Stx is the main pathogenic agent associated with typical hemolytic-uremic syndrome (HUS). In contrast to the detailed information describing the molecular basis for EHEC adherence to epithelial cells, very little is known about how Stx is released from bacteria in the gut, reaching its target tissues, mainly the kidney and central nervous system (CNS). In order to develop an efficient treatment for EHEC infections, it is necessary to understand the mechanisms involved in Stx expression. In this regard, the present study demonstrates that mammals can synthesize biologically active Stx using the natural promoter associated with the Stx-converting bacteriophage genome. These results could impact the comprehension of EHEC HUS, since local eukaryotic cells transduced and/or infected by bacteriophage encoding Stx2 could be an alternative source of Stx production.

scholarly journals Whole-genome characterization of hemolytic uremic syndrome-causing Shiga toxin-producing Escherichia coli in Sweden

Virulence ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 1296-1305
Author(s):  
Ying Hua ◽  
Milan Chromek ◽  
Anne Frykman ◽  
Cecilia Jernberg ◽  
Valya Georgieva ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hemolytic Uremic Syndrome ◽  
Shiga Toxin ◽  
Whole Genome ◽  
Genome Characterization ◽  
Uremic Syndrome

Outbreak of Shiga Toxin–Producing Escherichia coli (STEC) O104:H4 Infection in Germany Causes a Paradigm Shift with Regard to Human Pathogenicity of STEC Strains

2012 ◽  
Vol 75 (2) ◽  
pp. 408-418 ◽  
Author(s):  
LOTHAR BEUTIN ◽  
ANNETT MARTIN
Keyword(s):  
Escherichia Coli ◽  
Hemolytic Uremic Syndrome ◽  
Shiga Toxin ◽  
Outbreak Strain ◽  
Fenugreek Seeds ◽  
E Coli ◽  
Aggregative Adherence ◽  
Uremic Syndrome ◽  
Enterocyte Effacement ◽  
The Way

An outbreak that comprised 3,842 cases of human infections with enteroaggregative hemorrhagic Escherichia coli (EAHEC) O104:H4 occurred in Germany in May 2011. The high proportion of adults affected in this outbreak and the unusually high number of patients that developed hemolytic uremic syndrome makes this outbreak the most dramatic since enterohemorrhagic E. coli (EHEC) strains were first identified as agents of human disease. The characteristics of the outbreak strain, the way it spread among humans, and the clinical signs resulting from EAHEC infections have changed the way Shiga toxin–producing E. coli strains are regarded as human pathogens in general. EAHEC O104:H4 is an emerging E. coli pathotype that is endemic in Central Africa and has spread to Europe and Asia. EAHEC strains have evolved from enteroaggregative E. coli by uptake of a Shiga toxin 2a (Stx2a)–encoding bacteriophage. Except for Stx2a, no other EHEC-specific virulence markers including the locus of enterocyte effacement are present in EAHEC strains. EAHEC O104:H4 colonizes humans through aggregative adherence fimbrial pili encoded by the enteroaggregative E. coli plasmid. The aggregative adherence fimbrial colonization mechanism substitutes for the locus of enterocyte effacement functions for bacterial adherence and delivery of Stx2a into the human intestine, resulting clinically in hemolytic uremic syndrome. Humans are the only known natural reservoir known for EAHEC. In contrast, Shiga toxin–producing E. coli and EHEC are associated with animals as natural hosts. Contaminated sprouted fenugreek seeds were suspected as the primary vehicle of transmission of the EAHEC O104:H4 outbreak strain in Germany. During the outbreak, secondary transmission (human to human and human to food) was important. Epidemiological investigations revealed fenugreek seeds as the source of entry of EAHEC O104:H4 into the food chain; however, microbiological analysis of seeds for this pathogen produced negative results. The survival of EAHEC in seeds and the frequency of human carriers of EAHEC should be investigated for a better understanding of EAHEC transmission routes.

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