The Science of Shiga Toxin-Producing (Verotoxin-Producing) Escherichia coli (STEC): An Ongoing One Health Journey toward Improved Health and Food Safety

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Gut Microbiota".

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 8713

Special Issue Editors

Agriculture and Agri-Food Canada, Lethbridge, AB T1J 4B1, Canada
Interests: environmental performance of extensive and intensive livestock farming practices; land use life cycle assessment of livestock production systems and industries
Special Issues, Collections and Topics in MDPI journals
Department of Biological Sciences, University of Lethbridge, 4401 University Dr., Lethbridge, AB T1K 3M4, Canada
Interests: food and feed-borne pathogens; Escherichia coli; ergot alkaloids
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Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2R3, Canada
Interests: Escherichia coli; gastroenteritis; foodborne pathogens; molecular epidemiology
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Canadian Food Inspection Agency, Lethbridge Laboratory, Lethbridge, AB, Canada
Interests: genomics; machine learning; bioinformatics; microbiology
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Department of Pediatric Nephrology, Amalia Children’s Hospital, Radboud University Medical Center Nijmegen, Nijmegen, The Netherlands
Interests: kidney disease; pediatrics; hemolytic uremic syndrome; thrombotic microangiopathy; complement
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Department of Bacteria, Parasites, and Fungi, Unit of Foodborne Infections, Statens Serum Institute, Copenhagen, Denmark
Interests: molecular microbiology; pathogens; infection control
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Enteric Diseases Epidemiology Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
Interests: illnesses caused by enteric bacteria (Campylobacter, Clostridium botulinum, E. coli, Listeria, Salmonella, Shigella, Vibrio, and other bacteria)
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Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, MN 55455, USA
Interests: infectious disease epidemiology; foodborne infections; enteric infections; zoonoses; molecular epidemiology

Special Issue Information

Dear Colleagues,

Verotoxigenic Escherichia coli (VTEC), also called Shiga toxin-producing Escherichia coli (STEC), are major pathogens transmitted by food, water, animals and their environment, and directly from one person to another. They typically cause diarrheal illness but can also cause severe systemic disease, particularly in children and the elderly. Virulence is associated with a type III secretion system, which enables injection of bacterial effector proteins into host cells. In addition, Shiga toxins damage the kidneys and cause the hemolytic uremic syndrome (HUS). No specific treatment is available for STEC infection. A better understanding of the pathogenesis and epidemiology of STEC infection is needed with an emphasis on One Health-approach solutions to the disease. This includes improved detection, understanding of reservoirs, control and detection in the food chain, and an understanding of STEC ecology.  For this Special Issue, we invite researchers to submit a review or original research article related to STEC detection, pathogenesis, epidemiology, ecology, or food safety that reflects the scientific community’s continued efforts to prevent and ameliorate STEC infections.

This Special Issue will contain papers related to STEC/VTEC research and will accompany the online meetings of VTEC 2022 (https://vtec2021.org/may-11-2021/). The in-person meeting of VTEC 2021 that was to be held in Banff, Alberta, Canada, has been rescheduled to May 2023 due to COVD-19. This online meeting will serve as a momentum-building event while we work towards meeting in person again soon.

Prof. Dr. Tim A. McAllister
Dr. Kim Stanford
Prof. Dr. Linda Chui
Dr. Chad R. Laing
Dr. Nicole Van De Kar
Dr. Flemming Scheutz
Dr. Patricia Griffin
Dr. Gillian Tarr
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Microorganisms is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • foodborne bacteria
  • bacterial pathogenesis
  • host-pathogen interactions
  • gut microbiota
  • STEC
  • VTEC E. coli
  • epidemiology
  • microbial ecology

Published Papers (7 papers)

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Editorial

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2 pages, 159 KiB  
Editorial
The Science of Shiga Toxin-Producing (Verotoxin-Producing) Escherichia coli (STEC): An Ongoing One Health Journey toward Improved Health and Food Safety—Editorial Summary
Microorganisms 2024, 12(2), 344; https://doi.org/10.3390/microorganisms12020344 - 07 Feb 2024
Viewed by 740
Abstract
Verotoxigenic Escherichia coli (VTEC), also termed Shiga toxin-producing Escherichia coli (STEC), is a human pathogen transmitted by food, water, animals, and their environment, and from one person to another [...] Full article

Research

Jump to: Editorial

12 pages, 1486 KiB  
Article
Identification and Characterization of ten Escherichia coli Strains Encoding Novel Shiga Toxin 2 Subtypes, Stx2n as Well as Stx2j, Stx2m, and Stx2o, in the United States
Microorganisms 2023, 11(10), 2561; https://doi.org/10.3390/microorganisms11102561 - 14 Oct 2023
Cited by 2 | Viewed by 1398
Abstract
The sharing of genome sequences in online data repositories allows for large scale analyses of specific genes or gene families. This can result in the detection of novel gene subtypes as well as the development of improved detection methods. Here, we used publicly [...] Read more.
The sharing of genome sequences in online data repositories allows for large scale analyses of specific genes or gene families. This can result in the detection of novel gene subtypes as well as the development of improved detection methods. Here, we used publicly available WGS data to detect a novel Stx subtype, Stx2n in two clinical E. coli strains isolated in the USA. During this process, additional Stx2 subtypes were detected; six Stx2j, one Stx2m strain, and one Stx2o, were all analyzed for variability from the originally described subtypes. Complete genome sequences were assembled from short- or long-read sequencing and analyzed for serotype, and ST types. The WGS data from Stx2n- and Stx2o-producing STEC strains were further analyzed for virulence genes pro-phage analysis and phage insertion sites. Nucleotide and amino acid maximum parsimony trees showed expected clustering of the previously described subtypes and a clear separation of the novel Stx2n subtype. WGS data were used to design OMNI PCR primers for the detection of all known stx1 (283 bp amplicon), stx2 (400 bp amplicon), intimin encoded by eae (221 bp amplicon), and stx2f (438 bp amplicon) subtypes. These primers were tested in three different laboratories, using standard reference strains. An analysis of the complete genome sequence showed variability in serogroup, virulence genes, and ST type, and Stx2 pro-phages showed variability in size, gene composition, and phage insertion sites. The strains with Stx2j, Stx2m, Stx2n, and Stx2o showed toxicity to Vero cells. Stx2j carrying strain, 2012C-4221, was induced when grown with sub-inhibitory concentrations of ciprofloxacin, and toxicity was detected. Taken together, these data highlight the need to reinforce genomic surveillance to identify the emergence of potential new Stx2 or Stx1 variants. The importance of this surveillance has a paramount impact on public health. Per our description in this study, we suggest that 2017C-4317 be designated as the Stx2n type-strain. Full article
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15 pages, 3117 KiB  
Article
Enzymatic Cleavage of Stx2a in the Gut and Identification of Pancreatic Elastase and Trypsin as Possible Main Cleavers
Microorganisms 2023, 11(10), 2487; https://doi.org/10.3390/microorganisms11102487 - 04 Oct 2023
Cited by 2 | Viewed by 891
Abstract
Shiga toxins (Stxs), especially the Stx2a subtype, are the major virulence factors involved in enterohemorrhagic Escherichia coli (EHEC)-associated hemolytic uremic syndrome (eHUS), a life-threatening disease causing acute kidney injury, especially in children. After oral transmission and colonization in the gut, EHEC release Stx. [...] Read more.
Shiga toxins (Stxs), especially the Stx2a subtype, are the major virulence factors involved in enterohemorrhagic Escherichia coli (EHEC)-associated hemolytic uremic syndrome (eHUS), a life-threatening disease causing acute kidney injury, especially in children. After oral transmission and colonization in the gut, EHEC release Stx. Intracellular cleavage of the Stx A subunit, when followed by reduction, boosts the enzymatic activity that causes damage to targeted cells. This cleavage was assumed to be mostly mediated by furin during Stx intracellular trafficking. To investigate whether this cleavage could occur in the intestine, even prior to entering target cells, Stx2a A subunit structure (intact or cleaved) was characterized after its exposure to specific host factors present in human stool. The molecular weight of Stx2a A subunit/fragments was determined by immunoblotting after electrophoretic separation under reducing conditions. In this study, it was demonstrated that Stx2a is cleaved by certain human stool components. Trypsin and chymotrypsin-like elastase 3B (CELA3B), two serine proteases, were identified as potential candidates that can trigger the extracellular cleavage of Stx2a A subunit directly after its secretion by EHEC in the gut. Whether the observed cleavage indeed translates to natural infections and plays a role in eHUS pathogenesis has yet to be determined. If so, it seems likely that a host’s protease profile could affect disease development by changing the toxin’s biological features. Full article
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11 pages, 973 KiB  
Article
Exploring Long-Read Metagenomics for Full Characterization of Shiga Toxin-Producing Escherichia coli in Presence of Commensal E. coli
Microorganisms 2023, 11(8), 2043; https://doi.org/10.3390/microorganisms11082043 - 09 Aug 2023
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Abstract
The characterization of Shiga toxin-producing Escherichia coli (STEC) is necessary to assess their pathogenic potential, but isolation of the strain from complex matrices such as milk remains challenging. In previous work, we have shown the potential of long-read metagenomics to characterize eae-positive [...] Read more.
The characterization of Shiga toxin-producing Escherichia coli (STEC) is necessary to assess their pathogenic potential, but isolation of the strain from complex matrices such as milk remains challenging. In previous work, we have shown the potential of long-read metagenomics to characterize eae-positive STEC from artificially contaminated raw milk without isolating the strain. The presence of multiple E. coli strains in the sample was shown to potentially hinder the correct characterization of the STEC strain. Here, we aimed at determining the STEC:commensal ratio that would prevent the characterization of the STEC. We artificially contaminated pasteurized milk with different ratios of an eae-positive STEC and a commensal E. coli and applied the method previously developed. Results showed that the STEC strain growth was better than the commensal E. coli after enrichment in acriflavine-supplemented BPW. The STEC was successfully characterized in all samples with at least 10 times more STEC post-enrichment compared to the commensal E. coli. However, the presence of equivalent proportions of STEC and commensal E. coli prevented the full characterization of the STEC strain. This study confirms the potential of long-read metagenomics for STEC characterization in an isolation-free manner while refining its limit regarding the presence of background E. coli strains. Full article
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16 pages, 3378 KiB  
Article
Differences in the Shiga Toxin (Stx) 2a Phage Regulatory Switch Region Influence Stx2 Localization and Virulence of Stx-Producing Escherichia coli in Mice
Microorganisms 2023, 11(8), 1925; https://doi.org/10.3390/microorganisms11081925 - 28 Jul 2023
Viewed by 905
Abstract
Shiga toxin (Stx)-producing Escherichia coli (STEC) is a major cause of foodborne illness globally, and infection with serotype O157:H7 is associated with increased risk of hospitalization and death in the U.S. The Stxs are encoded on a temperate bacteriophage (stx-phage), and [...] Read more.
Shiga toxin (Stx)-producing Escherichia coli (STEC) is a major cause of foodborne illness globally, and infection with serotype O157:H7 is associated with increased risk of hospitalization and death in the U.S. The Stxs are encoded on a temperate bacteriophage (stx-phage), and phage induction leads to Stx expression; subtype Stx2a in particular is associated with more severe disease. Our earlier studies showed significant levels of RecA-independent Stx2 production by STEC O157:H7 strain JH2010 (stx2astx2c), even though activated RecA is the canonical trigger for stx-phage induction. This study aimed to further compare and contrast RecA-independent toxin production in Stx2-producing clinical isolates. Deletion of recA in JH2010 resulted in higher in vitro supernatant cytotoxicity compared to that from JH2016ΔrecA, and the addition of the chelator ethylenediaminetetraacetic acid (EDTA) and various metal cations to the growth medium exacerbated the difference in cytotoxicity exhibited by the two deletion strains. Both the wild-type and ΔrecA deletion strains exhibited differential cytotoxicity in the feces of infected, streptomycin (Str)-treated mice. Comparison of the stx2a-phage predicted protein sequences from JH2010 and JH2016 revealed low amino acid identity of key phage regulatory proteins that are involved in RecA-mediated stx-phage induction. Additionally, other STEC isolates containing JH2010-like and JH2016-like stx2a-phage sequences led to similar Stx2 localization, as demonstrated by JH2010ΔrecA and JH2016ΔrecA, respectively. Deletion of the stx2a-phage regulatory region in the wild-type strains prevented the differential localization of Stx2 into the culture supernatant, a finding that suggests that the stx2a-phage regulatory region is involved in the differential ΔrecA phenotypes exhibited by the two strains. We hypothesize that the amino acid differences between the JH2010 and JH2016 phage repressor proteins (CIs) lead to structural differences that are responsible for differential interaction with RecA. Overall, we discovered that non-homologous stx2a-phage regulatory proteins differentially influence RecA-independent, and possibly RecA-dependent, Stx2 production. These findings emphasize the importance of studying non-homologous regulatory elements among stx2-phages and their influence on Stx2 production and virulence of STEC isolates. Full article
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12 pages, 1108 KiB  
Article
Shiga Toxin-Producing Escherichia coli (STEC) Associated with Calf Mortality in Uruguay
Microorganisms 2023, 11(7), 1704; https://doi.org/10.3390/microorganisms11071704 - 29 Jun 2023
Viewed by 1058
Abstract
In Uruguay, the mortality of dairy calves due to infectious diseases is high. Escherichia coli is a natural inhabitant of the intestinal microbiota, but can cause several infections. The aim of the work was to characterize E. coli isolates from intestinal and extraintestinal [...] Read more.
In Uruguay, the mortality of dairy calves due to infectious diseases is high. Escherichia coli is a natural inhabitant of the intestinal microbiota, but can cause several infections. The aim of the work was to characterize E. coli isolates from intestinal and extraintestinal origin of dead newborn calves. Using PCR, virulence gene characteristics of pathogenic E. coli were searched. The pathogenic E. coli were molecularly characterized and the phylogroup, serogroup and the Stx subtype were determined. Antibiotic susceptibility was determined using the Kirby–Bauer disk diffusion method and plasmid-mediated quinolone resistance (PMQR) genes with PCR. Finally, clonal relationships were inferred using PFGE. Gene characteristics of the Shiga toxin-producing E. coli (STEC), Enteropathogenic E. coli (EPEC) and Necrotoxigenic E. coli (NTEC) were identified. The prevalence of the iucD, afa8E, f17, papC, stx1, eae and ehxA genes was high and no f5, f41, saa, sfaDE, cdtIV, lt, sta or stx2 were detected. The prevalence of STEC gene stx1 in the dead calves stood out and was higher compared with previous studies conducted in live calves, and STEC LEE+ (Enterohemorrhagic E. coli (EHEC)) isolates with stx1/eae/ehxA genotypes were more frequently identified in the intestinal than in the extraintestinal environment. E. coli isolates were assigned to phylogroups A, B1, D and E, and some belonged to the O111 serogroup. stx1a and stx1c subtypes were determined in STEC. A high prevalence of multi-resistance among STEC and qnrB genes was determined. The PFGE showed a high diversity of pathogenic strains with similar genetic profiles. It can be speculated that EHEC (stx1/eae/ehxA) could play an important role in mortality. The afa8E, f17G1 and papC genes could also have a role in calf mortality. Multidrug resistance defies disease treatment and increases the risk of death, while the potential transmissibility of genes to other species constitutes a threat to public health. Full article
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13 pages, 1008 KiB  
Article
Prevalence and Characterization of Shiga Toxin Producing Escherichia coli Isolated from Animal Feed in Croatia
Microorganisms 2022, 10(9), 1839; https://doi.org/10.3390/microorganisms10091839 - 14 Sep 2022
Cited by 2 | Viewed by 1848
Abstract
A survey on prevalence and number of Shiga toxin-producing Escherichia (E.) coli (STEC) in animal feed was carried out over a period of nine years in the Republic of Croatia. A total of 1688 feed samples were collected from feed factories [...] Read more.
A survey on prevalence and number of Shiga toxin-producing Escherichia (E.) coli (STEC) in animal feed was carried out over a period of nine years in the Republic of Croatia. A total of 1688 feed samples were collected from feed factories and poultry farms. Analysis included two standard procedures: sample enrichment and (a) immunomagnetic separation and plating on two selective media; or (b) plating on two selective media. Confirmation of STEC included morphological examination, biochemical tests, serotyping, and polymerase chain reaction. Morphological and biochemical characterization revealed 629 E. coli strains. Further serological screening method revealed 78 STEC and EPEC serotypes, while only 27 strains were confirmed as STEC with PCR. All positive samples (1.6%) originated from poultry farms and contained combination of virulence genes: eaeA, stx1, and/or stx2. Since the presence of stx (especially stx2) and eae are identified as risk factors for development of severe diseases in humans, results of this survey indicate that avian sources of STEC infections might be one of those “undefined sources” of human illnesses. Further research is necessary for evaluation of risks posed by contaminated feed, poultry, and environment. Full article
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