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 Fate of Escherichia coli O26 in Corn Silage Experimentally Contaminated at Ensiling, at Silo Opening, or after Aerobic Exposure, and Protective Effect of Various Bacterial Inoculants

2011 ◽  
Vol 77 (24) ◽  
pp. 8696-8704 ◽  
Author(s):  
Lysiane Dunière ◽  
Audrey Gleizal ◽  
Frédérique Chaucheyras-Durand ◽  
Isabelle Chevallier ◽  
Delphine Thévenot-Sergentet
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Leuconostoc Mesenteroides ◽  
Corn Silage ◽  
Content Type ◽  
Cattle Feed ◽  
E Coli ◽  
Bacterial Inoculants ◽  
Nutritional Qualities ◽  
Human Illness

ABSTRACTShiga toxin-producingEscherichia coli(STEC) strains are responsible for human illness. Ruminants are recognized as a major reservoir of STEC, and animal feeds, such as silages, have been pointed out as a possible vehicle for the spread of STEC. The present study aimed to monitor the fate of pathogenicE. coliO26 strains in corn material experimentally inoculated (105CFU/g) during ensiling, just after silo opening, and after several days of aerobic exposure. The addition of 3 bacterial inoculants,Propionibacteriumsp.,Lactobacillus buchneri, andLeuconostoc mesenteroides(106CFU/g), was evaluated for their abilities to control these pathogens. The results showed thatE. coliO26 could not survive in corn silage 5 days postensiling, and the 3 inoculants tested did not modify the fate of pathogen survival during ensiling. In the case of direct contamination at silo opening,E. coliO26 could be totally eradicated from corn silage previously inoculated withLeuconostoc mesenteroides. The combination of proper ensiling techniques and the utilization of selected bacterial inoculants appears to represent a good strategy to guarantee nutritional qualities of cattle feed while at the same time limiting the entry of pathogenicE. coliinto the epidemiological cycle to improve the microbial safety of the food chain.

scholarly journals Antibiotic-Mediated Modulations of Outer Membrane Vesicles in Enterohemorrhagic Escherichia coli O104:H4 and O157:H7

2017 ◽  
Vol 61 (9) ◽  
Author(s):  
Andreas Bauwens ◽  
Lisa Kunsmann ◽  
Helge Karch ◽  
Alexander Mellmann ◽  
Martina Bielaszewska
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Shiga Toxin ◽  
Membrane Vesicles ◽  
Polymyxin B ◽  
Outer Membrane Vesicles ◽  
Enterohemorrhagic Escherichia Coli ◽  
Content Type ◽  
E Coli ◽  
Major Virulence Factor

ABSTRACT Ciprofloxacin, meropenem, fosfomycin, and polymyxin B strongly increase production of outer membrane vesicles (OMVs) in Escherichia coli O104:H4 and O157:H7. Ciprofloxacin also upregulates OMV-associated Shiga toxin 2a, the major virulence factor of these pathogens, whereas the other antibiotics increase OMV production without the toxin. These two effects might worsen the clinical outcome of infections caused by Shiga toxin-producing E. coli. Our data support the existing recommendations to avoid antibiotics for treatment of these infections.

scholarly journals Genome Sequence of a T4-like Phage, Escherichia Phage vB_EcoM-Sa45lw, Infecting Shiga Toxin-Producing Escherichia coli Strains

2019 ◽  
Vol 8 (32) ◽  
Author(s):  
Yen-Te Liao ◽  
Yujie Zhang ◽  
Alexandra Salvador ◽  
Vivian C. H. Wu
Keyword(s):  
Escherichia Coli ◽  
Surface Water ◽  
Genome Size ◽  
Shiga Toxin ◽  
Open Reading Frames ◽  
Content Type ◽  
E Coli ◽  
Double Stranded Dna ◽  
A Genome ◽  
Reading Frames

Escherichia phage vB_EcoM-Sa45lw, a new member of the T4-like phages, was isolated from surface water in a produce-growing area. The phage, containing double-stranded DNA with a genome size of 167,353 bp and 282 predicted open reading frames (ORFs), is able to infect generic Escherichia coli and Shiga toxin-producing E. coli O45 and O157 strains.

scholarly journals A Toxic Environment: a Growing Understanding of How Microbial Communities Affect Escherichia coli O157:H7 Shiga Toxin Expression

2020 ◽  
Vol 86 (24) ◽  
Author(s):  
Erin M. Nawrocki ◽  
Hillary M. Mosso ◽  
Edward G. Dudley
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Microbial Interactions ◽  
Severe Illness ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Lambdoid Prophage

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) strains, including E. coli O157:H7, cause severe illness in humans due to the production of Shiga toxin (Stx) and other virulence factors. Because Stx is coregulated with lambdoid prophage induction, its expression is especially susceptible to environmental cues. Infections with Stx-producing E. coli can be difficult to model due to the wide range of disease outcomes: some infections are relatively mild, while others have serious complications. Probiotic organisms, members of the gut microbiome, and organic acids can depress Stx production, in many cases by inhibiting the growth of EHEC strains. On the other hand, the factors currently known to amplify Stx act via their effect on the stx-converting phage. Here, we characterize two interactive mechanisms that increase Stx production by O157:H7 strains: first, direct interactions with phage-susceptible E. coli, and second, indirect amplification by secreted factors. Infection of susceptible strains by the stx-converting phage can expand the Stx-producing population in a human or animal host, and phage infection has been shown to modulate virulence in vitro and in vivo. Acellular factors, particularly colicins and microcins, can kill O157:H7 cells but may also trigger Stx expression in the process. Colicins, microcins, and other bacteriocins have diverse cellular targets, and many such molecules remain uncharacterized. The identification of additional Stx-amplifying microbial interactions will improve our understanding of E. coli O157:H7 infections and help elucidate the intricate regulation of pathogenicity in EHEC strains.

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 Assessment of Shiga Toxin-Producing Escherichia coli Isolates from Wildlife Meat as Potential Pathogens for Humans

2009 ◽  
Vol 75 (20) ◽  
pp. 6462-6470 ◽  
Author(s):  
Angelika Miko ◽  
Karin Pries ◽  
Sabine Haby ◽  
Katja Steege ◽  
Nadine Albrecht ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Farm Animals ◽  
Clonal Lineage ◽  
E Coli ◽  
Virulence Markers ◽  
Potential Source ◽  
Human Illness ◽  
High Level ◽  
Game Animals

ABSTRACT A total of 140 Shiga toxin-producing Escherichia coli (STEC) strains from wildlife meat (deer, wild boar, and hare) isolated in Germany between 1998 and 2006 were characterized with respect to their serotypes and virulence markers associated with human pathogenicity. The strains grouped into 38 serotypes, but eight O groups (21, 146, 128, 113, 22, 88, 6, and 91) and four H types (21, 28, 2, and 8) accounted for 71.4% and 75.7% of all STEC strains from game, respectively. Eighteen of the serotypes, including enterohemorrhagic E. coli (EHEC) O26:[H11] and O103:H2, were previously found to be associated with human illness. Genes linked to high-level virulence for humans (stx 2, stx 2d, and eae) were present in 46 (32.8%) STEC strains from game. Fifty-four STEC isolates from game belonged to serotypes which are frequently found in human patients (O103:H2, O26:H11, O113:H21, O91:H21, O128:H2, O146:H21, and O146:H28). These 54 STEC isolates were compared with 101 STEC isolates belonging to the same serotypes isolated from farm animals, from their food products, and from human patients. Within a given serotype, most STEC strains were similar with respect to their stx genotypes and other virulence attributes, regardless of origin. The 155 STEC strains were analyzed for genetic similarity by XbaI pulsed-field gel electrophoresis. O103:H2, O26:H11, O113:H21, O128:H2, and O146:H28 STEC isolates from game were 85 to 100% similar to STEC isolates of the same strains from human patients. By multilocus sequence typing, game EHEC O103:H2 strains were attributed to a clonal lineage associated with hemorrhagic diseases in humans. The results from our study indicate that game animals represent a reservoir for and a potential source of human pathogenic STEC and EHEC strains.

scholarly journals The Accessory Genome of Shiga Toxin-Producing Escherichia coli Defines a Persistent Colonization Type in Cattle

2016 ◽  
Vol 82 (17) ◽  
pp. 5455-5464 ◽  
Author(s):  
Stefanie A. Barth ◽  
Christian Menge ◽  
Inga Eichhorn ◽  
Torsten Semmler ◽  
Lothar H. Wieler ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Intervention Strategies ◽  
Content Type ◽  
Accessory Genome ◽  
Farm Level ◽  
E Coli ◽  
Zoonotic Pathogens ◽  
Human Risk ◽  
Genetic Patterns

ABSTRACTShiga toxin-producingEscherichia coli(STEC) strains can colonize cattle for several months and may, thus, serve as gene reservoirs for the genesis of highly virulent zoonotic enterohemorrhagicE. coli(EHEC). Attempts to reduce the human risk for acquiring EHEC infections should include strategies to control such STEC strains persisting in cattle. We therefore aimed to identify genetic patterns associated with the STEC colonization type in the bovine host. We included 88 persistent colonizing STEC (STECper) (shedding for ≥4 months) and 74 sporadically colonizing STEC (STECspo) (shedding for ≤2 months) isolates from cattle and 16 bovine STEC isolates with unknown colonization types. Genoserotypes and multilocus sequence types (MLSTs) were determined, and the isolates were probed with a DNA microarray for virulence-associated genes (VAGs). All STECperisolates belonged to only four genoserotypes (O26:H11, O156:H25, O165:H25, O182:H25), which formed three genetic clusters (ST21/396/1705, ST300/688, ST119). In contrast, STECspoisolates were scattered among 28 genoserotypes and 30 MLSTs, with O157:H7 (ST11) and O6:H49 (ST1079) being the most prevalent. The microarray analysis identified 139 unique gene patterns that clustered with the genoserotypes and MLSTs of the strains. While the STECperisolates possessed heterogeneous phylogenetic backgrounds, the accessory genome clustered these isolates together, separating them from the STECspoisolates. Given the vast genetic heterogeneity of bovine STEC strains, defining the genetic patterns distinguishing STECperfrom STECspoisolates will facilitate the targeted design of new intervention strategies to counteract these zoonotic pathogens at the farm level.IMPORTANCERuminants, especially cattle, are sources of food-borne infections by Shiga toxin-producingEscherichia coli(STEC) in humans. Some STEC strains persist in cattle for longer periods of time, while others are detected only sporadically. Persisting strains can serve as gene reservoirs that supplyE. coliwith virulence factors, thereby generating new outbreak strains. Attempts to reduce the human risk for acquiring STEC infections should therefore include strategies to control such persisting STEC strains. By analyzing representative genes of their core and accessory genomes, we show that bovine STEC with a persistent colonization type emerged independently from sporadically colonizing isolates and evolved in parallel evolutionary branches. However, persistent colonizing strains share similar sets of accessory genes. Defining the genetic patterns that distinguish persistent from sporadically colonizing STEC isolates will facilitate the targeted design of new intervention strategies to counteract these zoonotic pathogens at the farm level.

scholarly journals Shiga Toxin-Producing Escherichia coli O104:H4: a New Challenge for Microbiology

2012 ◽  
Vol 78 (12) ◽  
pp. 4065-4073 ◽  
Author(s):  
Maite Muniesa ◽  
Jens A. Hammerl ◽  
Stefan Hertwig ◽  
Bernd Appel ◽  
Harald Brüssow
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Supportive Therapy ◽  
Intestinal Barrier ◽  
Virulence Plasmid ◽  
Complement Protein ◽  
Content Type ◽  
E Coli ◽  
Randomized Controlled Clinical Trials ◽  
Lambdoid Prophage

ABSTRACTIn 2011, Germany experienced the largest outbreak with a Shiga toxin-producingEscherichia coli(STEC) strain ever recorded. A series of environmental and trace-back and trace-forward investigations linked sprout consumption with the disease, but fecal-oral transmission was also documented. The genome sequences of the pathogen revealed a clonal outbreak with enteroaggregativeE. coli(EAEC). Some EAEC virulence factors are carried on the virulence plasmid pAA. From an unknown source, the epidemic strains acquired a lambdoid prophage carrying the gene for the Shiga toxin. The resulting strains therefore possess two different mobile elements, a phage and a plasmid, contributing essential virulence genes. Shiga toxin is released by decaying bacteria in the gut, migrates through the intestinal barrier, and is transported via the blood to target organs, like the kidney. In a mouse model, probiotic bifidobacteria interfered with transport of the toxin through the gut mucosa. Researchers explored bacteriophages, bacteriocins, and low-molecular-weight inhibitors against STEC. Randomized controlled clinical trials of enterohemorrhagicE. coli(EHEC)-associated hemolytic uremic syndrome (HUS) patients found none of the interventions superior to supportive therapy alone. Antibodies against one subtype of Shiga toxin protected pigs against fatal neurological infection, while treatment with a toxin receptor decoy showed no effect in a clinical trial. Likewise, a monoclonal antibody directed against a complement protein led to mixed results. Plasma exchange and IgG immunoadsoprtion ameliorated the condition in small uncontrolled trials. The epidemic O104:H4 strains were resistant to all penicillins and cephalosporins but susceptible to carbapenems, which were recommended for treatment.

scholarly journals CTX-M-15 Extended-Spectrum β-Lactamase in a Shiga Toxin-Producing Escherichia coli Isolate of Serotype O111:H8

2011 ◽  
Vol 78 (4) ◽  
pp. 1308-1309 ◽  
Author(s):  
Charlotte Valat ◽  
Marisa Haenni ◽  
Estelle Saras ◽  
Frédéric Auvray ◽  
Karine Forest ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Content Type ◽  
Coli Isolate ◽  
E Coli ◽  
Extended Spectrum

ABSTRACTWe report the discovery of a CTX-M-15-producingEscherichia coli(STEC) of serogroup O111:H8, a major serotype responsible for human enterohemorrhagicEscherichia coli(EHEC) infections. In line with the recent CTX-M-15/O104:H4E. colioutbreak, these data may reflect an accelerating spread of resistance to expanded-spectrum cephalosporins within theE. colipopulation, including STEC isolates.

scholarly journals Genome Signatures of Escherichia coli O157:H7 Isolates from the Bovine Host Reservoir

2011 ◽  
Vol 77 (9) ◽  
pp. 2916-2925 ◽  
Author(s):  
Mark Eppinger ◽  
Mark K. Mammel ◽  
Joseph E. LeClerc ◽  
Jacques Ravel ◽  
Thomas A. Cebula
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Phylogenomic Analysis ◽  
Genotypic Differences ◽  
Pathogenic Potential ◽  
Content Type ◽  
E Coli ◽  
A Genome ◽  
Major Interest ◽  
Host Reservoir

ABSTRACTCattle comprise a main reservoir of Shiga toxin-producingEscherichia coliO157:H7 (STEC). The significant differences in host prevalence, transmissibility, and virulence phenotypes among strains from bovine and human sources are of major interest to the public health community and livestock industry. Genomic analysis revealed divergence into three lineages: lineage I and lineage I/II strains are commonly associated with human disease, while lineage II strains are overrepresented in the asymptomatic bovine host reservoir. Growing evidence suggests that genotypic differences between these lineages, such as polymorphisms in Shiga toxin subtypes and synergistically acting virulence factors, are correlated with phenotypic differences in virulence, host ecology, and epidemiology. To assess the genomic plasticity on a genome-wide scale, we have sequenced the whole genome of strain EC869, a bovine-associatedE. coliO157:H7 isolate. Comparative phylogenomic analysis of this key isolate enabled us to place accurately bovine lineage II strains within the genetically homogenousE. coliO157:H7 clade. Identification of polymorphic loci that are anchored both in the chromosomal backbone and horizontally acquired regions allowed us to associate bovine genotypes with altered virulence phenotypes and host prevalence. This study catalogued numerous novel lineage II-specific genome signatures, some of which appear to be associated intimately with the altered pathogenic potential and niche adaptation within the bovine rumen. The presented extended list of polymorphic markers is valuable in the development of a robust typing system critical for forensic, diagnostic, and epidemiological studies of this emerging human pathogen.

Sign in / Sign up

Export Citation Format

Share Document