scholarly journals Prevalences of Shiga Toxin Subtypes and Selected Other Virulence Factors among Shiga-Toxigenic Escherichia coli Strains Isolated from Fresh Produce

2013 ◽  
Vol 79 (22) ◽  
pp. 6917-6923 ◽  
Author(s):  
Peter C. H. Feng ◽  
Shanker Reddy
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Virulence Factor ◽  
Shiga Toxin ◽  
Fresh Produce ◽  
Putative Virulence Factor ◽  
Content Type ◽  
Human Illness ◽  
Subtilase Cytotoxin ◽  
Virulence Factor Genes

ABSTRACTShiga-toxigenicEscherichia coli(STEC) strains were isolated from a variety of fresh produce, but mostly from spinach, with an estimated prevalence rate of 0.5%. A panel of 132 produce STEC strains were characterized for the presence of virulence and putative virulence factor genes and for Shiga toxin subtypes. About 9% of the isolates were found to have theeaegene, which encodes the intimin binding protein, and most of these belonged to known pathogenic STEC serotypes, such as O157:H7 and O26:H11, or to serotypes that reportedly have caused human illness. Among theeae-negative strains, there were three O113:H21 strains and one O91:H21 strain, which historically have been implicated in illness and therefore may be of concern as well. TheehxAgene, which encodes enterohemolysin, was found in ∼60% of the isolates, and thesaaandsubABgenes, which encode STEC agglutinating adhesin and subtilase cytotoxin, respectively, were found in ∼30% of the isolates. However, the precise roles of these three putative virulence factors in STEC pathogenesis have not yet been fully established. Thestx1aandstx2asubtypes were present in 22% and 56%, respectively, of the strains overall and were the most common subtypes among produce STEC strains. Thestx2dsubtype was the second most common subtype (28% overall), followed bystx2c(7.5%), and only 2 to 3% of the produce STEC strains had thestx2eandstx2gsubtypes. Almost half of the produce STEC strains had only partial serotypes or were untyped, and most of those that were identified belonged to unremarkable serotypes. Considering the uncertainties of some of these Stx subtypes and putative virulence factors in causing human illness, it is difficult to determine the health risk of many of these produce STEC strains.

scholarly journals Cytotoxic and Apoptotic Effects of Recombinant Subtilase Cytotoxin Variants of Shiga Toxin-Producing Escherichia coli

2015 ◽  
Vol 83 (6) ◽  
pp. 2338-2349 ◽  
Author(s):  
J. Funk ◽  
N. Biber ◽  
M. Schneider ◽  
E. Hauser ◽  
S. Enzenmüller ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Vero Cells ◽  
Toxic Activity ◽  
Content Type ◽  
B Subunits ◽  
Induced Apoptosis ◽  
The Individual ◽  
Apoptotic Effects ◽  
Subtilase Cytotoxin

In this study, the cytotoxicity of the recently described subtilase variant SubAB2-2of Shiga toxin-producingEscherichia coliwas determined and compared to the plasmid-encoded SubAB1and the chromosome-encoded SubAB2-1variant. The genes for the respective enzymatic active (A) subunits and binding (B) subunits of the subtilase toxins were amplified and cloned. The recombinant toxin subunits were expressed and purified. Their cytotoxicity on Vero cells was measured for the single A and B subunits, as well as for mixtures of both, to analyze whether hybrids with toxic activity can be identified. The results demonstrated that all three SubAB variants are toxic for Vero cells. However, the values for the 50% cytotoxic dose (CD50) differ for the individual variants. Highest cytotoxicity was shown for SubAB1. Moreover, hybrids of subunits from different subtilase toxins can be obtained which cause substantial cytotoxicity to Vero cells after mixing the A and B subunits prior to application to the cells, which is characteristic for binary toxins. Furthermore, higher concentrations of the enzymatic subunit SubA1exhibited cytotoxic effects in the absence of the respective B1subunit. A more detailed investigation in the human HeLa cell line revealed that SubA1alone induced apoptosis, while the B1subunit alone did not induce cell death.

Molecular characterization and prevalence of virulence factor genes of Shiga toxin-producing Escherichia coli (STEC) isolated from diarrheic children

Gene Reports ◽  
2021 ◽  
pp. 101379
Author(s):  
Mohammad Moeinirad ◽  
Masoumeh Douraghi ◽  
Abbas Rahimi Foroushani ◽  
Rahimeh Sanikhani ◽  
Mohammad Mehdi Soltan Dallal
Keyword(s):  
Escherichia Coli ◽  
Molecular Characterization ◽  
Virulence Factor ◽  
Shiga Toxin ◽  
Virulence Factor Genes

scholarly journals Transcription of the Subtilase Cytotoxin Gene subAB1 in Shiga Toxin-Producing Escherichia coli Is Dependent on hfq and hns

2019 ◽  
Vol 85 (20) ◽  
Author(s):  
Laura Heinisch ◽  
Katharina Zoric ◽  
Maike Krause ◽  
Herbert Schmidt
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Shiga Toxin ◽  
Promoter Activity ◽  
Deletion Mutants ◽  
Content Type ◽  
E Coli ◽  
Intensive Investigation ◽  
Subtilase Cytotoxin

ABSTRACT Certain foodborne Shiga toxin-producing Escherichia coli (STEC) strains carry genes encoding the subtilase cytotoxin (SubAB). Although the mode of action of SubAB is under intensive investigation, information about the regulation of subAB gene expression is currently not available. In this study, we investigated the regulation of the chromosomal subAB1 gene in laboratory E. coli strain DH5α and STEC O113:H21 strain TS18/08 using a luciferase reporter gene assay. Special emphasis was given to the role of the global regulatory protein genes hfq and hns in subAB1 promoter activity. Subsequently, quantitative real-time PCR was performed to analyze the expression of Shiga toxin 2a (Stx2a), SubAB1, and cytolethal distending toxin V (Cdt-V) genes in STEC strain TS18/08 and its isogenic hfq and hns deletion mutants. The deletion of hfq led to a significant increase of up to 2-fold in subAB1 expression, especially in the late growth phase, in both strains. However, deletion of hns showed different effects on the promoter activity during the early and late exponential growth phases in both strains. Furthermore, upregulation of stx2a and cdt-V was demonstrated in hfq and hns deletion mutants in TS18/08. These data showed that the expression of subAB1, stx2a, and cdt-V is integrated in the regulatory network of global regulators Hfq and H-NS in Escherichia coli. IMPORTANCE Shiga toxin-producing Escherichia coli (STEC) strains are responsible for outbreaks of foodborne diseases, such as hemorrhagic colitis and the hemolytic uremic syndrome. The pathogenicity of those strains can be attributed to, among other factors, the production of toxins. Recently, the subtilase cytotoxin was detected in locus of enterocyte effacement (LEE)-negative STEC, and it was confirmed that it contributes to the cytotoxicity of those STEC strains. Although the mode of action of SubAB1 is under intensive investigation, the regulation of gene expression is currently not known. The global regulatory proteins H-NS and Hfq have impact on many cellular processes and have been described to regulate virulence factors as well. Here, we investigate the role of hns and hfq in expression of subAB1 as well as stx2a and cdt-V in an E. coli laboratory strain as well as in wild-type STEC strain TS18/08.

scholarly journals Draft Genome Sequences of Five Shiga Toxin-Producing Escherichia coli Isolates Harboring the New and Recently Described Subtilase Cytotoxin Allelic Variant subAB2-3

2017 ◽  
Vol 5 (8) ◽  
Author(s):  
Taurai Tasara ◽  
Lisa Fierz ◽  
Jochen Klumpp ◽  
Herbert Schmidt ◽  
Roger Stephan
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Sequence Data ◽  
Draft Genome ◽  
Allelic Variant ◽  
Genome Sequences ◽  
Content Type ◽  
Subtilase Cytotoxin

ABSTRACT We present here the draft genome sequences of five Shiga toxin-producing Escherichia coli (STEC) strains which tested positive in a primary subAB screening. Assembly and annotation of the draft genomes revealed that all strains harbored the recently described allelic variant subAB 2-3 . Based on the sequence data, primers were designed to identify and differentiate this variant.

scholarly journals Inhibition of Water Absorption and Selective Damage to Human Colonic Mucosa Are Induced by Subtilase Cytotoxin Produced by Escherichia coli O113:H21

2013 ◽  
Vol 81 (8) ◽  
pp. 2931-2937 ◽  
Author(s):  
Elizabeth Gerhardt ◽  
Mariana Masso ◽  
Adrienne W. Paton ◽  
James C. Paton ◽  
Elsa Zotta ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Water Absorption ◽  
Shiga Toxin ◽  
Human Colon ◽  
Surface Epithelium ◽  
Inflammatory Infiltration ◽  
Content Type ◽  
Uremic Syndrome ◽  
Normal Water ◽  
Subtilase Cytotoxin

ABSTRACTShiga toxin-producingEscherichia coliO157:H7 (STEC) is by far the most prevalent serotype associated with hemolytic uremic syndrome (HUS) although many non-O157 STEC strains have been also isolated from patients with HUS. The main virulence factor of STEC is the Shiga toxin type 2 (Stx2) present in O157 and non-O157 strains. Recently, another toxin, named subtilase cytotoxin (SubAB), has been isolated from several non-O157 strains and may contribute to the pathogenesis of HUS. Here, we have demonstrated that an O113:H21 STEC strain expressing SubAB and Stx2 inhibits normal water absorption across human colon and causes damage to the surface epithelium, necrosis, mononuclear inflammatory infiltration, edema, and marked mucin depletion. This damage was less marked, but nevertheless significant, when purified SubAB orE. coliO113:H21 expressing only SubAB was assayed. This is the first study showing that SubAB may directly participate in the mechanisms of diarrhea in children infected with non-O157 STEC strains.

scholarly journals Simultaneous Presence of Insertion Sequence Excision Enhancer and Insertion Sequence IS629Correlates with Increased Diversity and Virulence in Shiga Toxin-Producing Escherichia coli

2015 ◽  
Vol 53 (11) ◽  
pp. 3466-3473 ◽  
Author(s):  
M. Toro ◽  
L. V. Rump ◽  
G. Cao ◽  
J. Meng ◽  
E. W. Brown ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Insertion Sequence ◽  
Family Members ◽  
Simultaneous Presence ◽  
Content Type ◽  
E Coli ◽  
Genomic Deletions ◽  
Human Illness ◽  
Hostile Environments

Although new serotypes of enterohemorrhagicEscherichia coli(EHEC) emerge constantly, the mechanisms by which these new pathogens arise and the reasons emerging serotypes tend to carry more virulence genes than otherE. coliare not understood. An insertion sequence (IS) excision enhancer (IEE) was discovered in EHEC O157:H7 that promoted the excision of IS3family members and generating various genomic deletions. One IS3family member, IS629, actively transposes and proliferates in EHEC O157:H7 and enterotoxigenicE. coli(ETEC) O139 and O149. The simultaneous presence of the IEE and IS629(and other IS3family members) may be part of a system promoting not only adaptation and genome diversification inE. coliO157:H7 but also contributing to the development of pathogenicity among predominant serotypes. Prevalence comparisons of these elements in 461 strains, representing 72 different serotypes and 5 preassigned seropathotypes (SPT) A to E, showed that the presence of these two elements simultaneously was serotype specific and associated with highly pathogenic serotypes (O157 and top non-O157 Shiga toxin-producing Escherichia coli [STEC]) implicated in outbreaks and sporadic cases of human illness (SPT A and B). Serotypes lacking one or both elements were less likely to have been isolated from clinical cases. Our comparisons of IEE sequences showed sequence variations that could be divided into at least three clusters. Interestingly, the IEE sequences from O157 and the top 10 non-O157 STEC serotypes fell into clusters I and II, while less commonly isolated serotypes O5 and O174 fell into cluster III. These results suggest that IS629and IEE elements may be acting synergistically to promote genome plasticity and genetic diversity among STEC strains, enhancing their abilities to adapt to hostile environments and rapidly take up virulence factors.

scholarly journals New Monoclonal Antibodies against a Novel Subtype of Shiga Toxin 1 Produced by Enterobacter cloacae and Their Use in Analysis of Human Serum

mSphere ◽  
2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Craig Skinner ◽  
Stephanie Patfield ◽  
Rowaida Khalil ◽  
Qiulian Kong ◽  
Xiaohua He
Keyword(s):  
Escherichia Coli ◽  
Monoclonal Antibodies ◽  
Human Serum ◽  
Virulence Factors ◽  
Shiga Toxin ◽  
Enterobacter Cloacae ◽  
Clinical Value ◽  
Content Type ◽  
Clinical Detection ◽  
Detection And Diagnosis

ABSTRACT Stxs are among the most clinically important virulence factors of Shigella and enterohemorrhagic Escherichia coli. There are many varieties of Stx, and although Stx1a and Stx2a are the most common and widely distributed types of Stx, new variants of Stx are continually emerging. These new variants of Stx can be challenging to detect, since most Stx detection kits are optimized for the detection of Stx1a and Stx2a. Stx1e, recently discovered in an atypical host (Enterobacter cloacae), is undetectable by many Stx assays. To formulate new assays for the detection of Stx1e, we generated four new MAbs that recognize this Stx subtype. Using these antibodies, we generated an assay capable of detecting Stx1e at low picogram-per-milliliter concentrations. This assay is also compatible with a human serum matrix, suggesting that it may have utility for the clinical detection and diagnosis of Stx1e-associated infections. Shiga toxin (Stx) is a major virulence factor of several bacterial pathogens that cause potentially fatal illness, including Escherichia coli and Shigella spp. The continual emergence of new subtypes of Stxs presents challenges for the clinical diagnosis of infections caused by Stx-producing organisms. Here, we report the development of four new monoclonal antibodies (MAbs) against Stx1e, a novel subtype of Stx1 that was produced by an Enterobacter cloacae strain and had limited reactivity with existing anti-Stx1 antibodies. Western blot analysis indicates that these MAbs were Stx1 specific, bound to the A subunit, and had distinct preferences for subtypes of Stx1. Of the four MAbs, Stx1e-2 was capable of partially neutralizing cytotoxicities derived from Stx1e in Vero cells. Enzyme-linked immunosorbent assays assembled with these high-affinity MAbs detected Stx1e at concentrations as low as 4.8 pg/ml in phosphate-buffered saline and 53.6 pg/ml in spiked human serum samples and were also capable of distinguishing Stx1e-producing strains in enriched cultures. These assays may therefore have clinical value in diagnosing Stx1e-producing bacterial infection. Additionally, characteristics of Stx1e, such as the origin of stx1e genes, conditions for toxin expression, receptor binding, and cytotoxicity, were investigated with the new antibodies developed in this study. This information should be useful for further understanding the clinical significance and prevalence of Stx1e-harboring E. cloacae and other organisms. IMPORTANCE Stxs are among the most clinically important virulence factors of Shigella and enterohemorrhagic Escherichia coli. There are many varieties of Stx, and although Stx1a and Stx2a are the most common and widely distributed types of Stx, new variants of Stx are continually emerging. These new variants of Stx can be challenging to detect, since most Stx detection kits are optimized for the detection of Stx1a and Stx2a. Stx1e, recently discovered in an atypical host (Enterobacter cloacae), is undetectable by many Stx assays. To formulate new assays for the detection of Stx1e, we generated four new MAbs that recognize this Stx subtype. Using these antibodies, we generated an assay capable of detecting Stx1e at low picogram-per-milliliter concentrations. This assay is also compatible with a human serum matrix, suggesting that it may have utility for the clinical detection and diagnosis of Stx1e-associated infections.

scholarly journals Prevalence of Hemolysin Genes and Comparison ofehxASubtype Patterns in Shiga Toxin-Producing Escherichia coli (STEC) and Non-STEC Strains from Clinical, Food, and Animal Sources

2013 ◽  
Vol 79 (20) ◽  
pp. 6301-6311 ◽  
Author(s):  
Sandra C. Lorenz ◽  
Insook Son ◽  
Anna Maounounen-Laasri ◽  
Andrew Lin ◽  
Markus Fischer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Shiga Toxin ◽  
Phenotypic Expression ◽  
Food Sources ◽  
Polymorphism Analysis ◽  
Subtype C ◽  
Content Type ◽  
E Coli ◽  
Subtype A

ABSTRACTShiga toxin-producingEscherichia coli(STEC) belonging to certain serogroups (e.g., O157 and O26) can cause serious conditions like hemolytic-uremic syndrome (HUS), but other strains might be equally pathogenic. While virulence factors, likestxandeae, have been well studied, little is known about the prevalence of theE. colihemolysin genes (hlyA,ehxA,e-hlyA, andsheA) in association with these factors. Hemolysins are potential virulence factors, andehxAandhlyAhave been associated with human illness, but the significance ofsheAis unknown. Hence, 435E. colistrains belonging to 62 different O serogroups were characterized to investigate gene presence and phenotypic expression of hemolysis. We further investigatedehxAsubtype patterns inE. coliisolates from clinical, animal, and food sources. WhilesheAandehxAwere widely distributed,e-hlyAandhlyAwere rarely found. Most strains (86.7%) were hemolytic, and significantly more hemolytic (95%) than nonhemolytic strains (49%) carriedstxand/oreae(P< 0.0001).ehxAsubtyping, as performed by using PCR in combination with restriction fragment length polymorphism analysis, resulted in six closely related subtypes (>94.2%), with subtypes A/D beingeae-negative STECs and subtypes B, C, E, and Feaepositive. Unexpectedly,ehxAsubtype patterns differed significantly between isolates collected from different sources (P< 0.0001), suggesting that simple linear models of exposure and transmission need modification; animal isolates carried mostly subtypes A/C (39.3%/42.9%), food isolates carried mainly subtype A (81.9%), and clinical isolates carried mainly subtype C (66.4%). Certain O serogroups correlated with particularehxAsubtypes: subtype A with O104, O113, and O8; B exclusively with O157; C with O26, O111, and O121.

scholarly journals Virulence Profiling of Shiga Toxin-Producing Escherichia coli O111:NM Isolates from Cattle

2013 ◽  
Vol 79 (13) ◽  
pp. 4164-4165 ◽  
Author(s):  
Musafiri Karama ◽  
Carlton L. Gyles
Keyword(s):  
United States ◽  
Escherichia Coli ◽  
Virulence Factors ◽  
Shiga Toxin ◽  
Disease Outbreaks ◽  
The United States ◽  
Full Spectrum ◽  
Gene Markers ◽  
Content Type

ABSTRACTShiga toxin-producingEscherichia coli(STEC) O111:NM is an important serotype that has been incriminated in disease outbreaks in the United States. This study characterized cattle STEC O111:NM for virulence factors and markers by PCR. Major conclusions are that STEC O111:NM characterized in this study lacksstx2and the full spectrum ofnlegene markers, and it has an incomplete OI-122.

Sign in / Sign up

Export Citation Format

Share Document