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Álvarez RS, Gómez FD, Zotta E, Paton AW, Paton JC, Ibarra C, Sacerdoti F, Amaral MM. Combined Action of Shiga Toxin Type 2 and Subtilase Cytotoxin in the Pathogenesis of Hemolytic Uremic Syndrome. Toxins (Basel) 2021; 13:536. [PMID: 34437406 PMCID: PMC8402323 DOI: 10.3390/toxins13080536] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 11/17/2022] Open
Abstract
Shiga toxin-producing E. coli (STEC) produces Stx1 and/or Stx2, and Subtilase cytotoxin (SubAB). Since these toxins may be present simultaneously during STEC infections, the purpose of this work was to study the co-action of Stx2 and SubAB. Stx2 + SubAB was assayed in vitro on monocultures and cocultures of human glomerular endothelial cells (HGEC) with a human proximal tubular epithelial cell line (HK-2) and in vivo in mice after weaning. The effects in vitro of both toxins, co-incubated and individually, were similar, showing that Stx2 and SubAB contribute similarly to renal cell damage. However, in vivo, co-injection of toxins lethal doses reduced the survival time of mice by 24 h and mice also suffered a strong decrease in the body weight associated with a lowered food intake. Co-injected mice also exhibited more severe histological renal alterations and a worsening in renal function that was not as evident in mice treated with each toxin separately. Furthermore, co-treatment induced numerous erythrocyte morphological alterations and an increase of free hemoglobin. This work shows, for the first time, the in vivo effects of Stx2 and SubAB acting together and provides valuable information about their contribution to the damage caused in STEC infections.
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Affiliation(s)
- Romina S. Álvarez
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina; (R.S.Á.); (F.D.G.); (E.Z.); (C.I.); (F.S.)
| | - Fernando D. Gómez
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina; (R.S.Á.); (F.D.G.); (E.Z.); (C.I.); (F.S.)
| | - Elsa Zotta
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina; (R.S.Á.); (F.D.G.); (E.Z.); (C.I.); (F.S.)
- Cátedra de Fisiopatología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires 1113, Argentina
| | - Adrienne W. Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia; (A.W.P.); (J.C.P.)
| | - James C. Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia; (A.W.P.); (J.C.P.)
| | - Cristina Ibarra
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina; (R.S.Á.); (F.D.G.); (E.Z.); (C.I.); (F.S.)
| | - Flavia Sacerdoti
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina; (R.S.Á.); (F.D.G.); (E.Z.); (C.I.); (F.S.)
| | - María M. Amaral
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina; (R.S.Á.); (F.D.G.); (E.Z.); (C.I.); (F.S.)
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Desvaux M, Dalmasso G, Beyrouthy R, Barnich N, Delmas J, Bonnet R. Pathogenicity Factors of Genomic Islands in Intestinal and Extraintestinal Escherichia coli. Front Microbiol 2020; 11:2065. [PMID: 33101219 PMCID: PMC7545054 DOI: 10.3389/fmicb.2020.02065] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/05/2020] [Indexed: 12/20/2022] Open
Abstract
Escherichia coli is a versatile bacterial species that includes both harmless commensal strains and pathogenic strains found in the gastrointestinal tract in humans and warm-blooded animals. The growing amount of DNA sequence information generated in the era of "genomics" has helped to increase our understanding of the factors and mechanisms involved in the diversification of this bacterial species. The pathogenic side of E. coli that is afforded through horizontal transfers of genes encoding virulence factors enables this bacterium to become a highly diverse and adapted pathogen that is responsible for intestinal or extraintestinal diseases in humans and animals. Many of the accessory genes acquired by horizontal transfers form syntenic blocks and are recognized as genomic islands (GIs). These genomic regions contribute to the rapid evolution, diversification and adaptation of E. coli variants because they are frequently subject to rearrangements, excision and transfer, as well as to further acquisition of additional DNA. Here, we review a subgroup of GIs from E. coli termed pathogenicity islands (PAIs), a concept defined in the late 1980s by Jörg Hacker and colleagues in Werner Goebel's group at the University of Würzburg, Würzburg, Germany. As with other GIs, the PAIs comprise large genomic regions that differ from the rest of the genome by their G + C content, by their typical insertion within transfer RNA genes, and by their harboring of direct repeats (at their ends), integrase determinants, or other mobility loci. The hallmark of PAIs is their contribution to the emergence of virulent bacteria and to the development of intestinal and extraintestinal diseases. This review summarizes the current knowledge on the structure and functional features of PAIs, on PAI-encoded E. coli pathogenicity factors and on the role of PAIs in host-pathogen interactions.
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Affiliation(s)
- Mickaël Desvaux
- Université Clermont Auvergne, INRAE, MEDiS, Clermont-Ferrand, France
| | - Guillaume Dalmasso
- UMR Inserm 1071, USC-INRAE 2018, M2iSH, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Racha Beyrouthy
- UMR Inserm 1071, USC-INRAE 2018, M2iSH, Université Clermont Auvergne, Clermont-Ferrand, France
- Laboratoire de Bactériologie, CHU Clermont-Ferrand, Clermont-Ferrand, France
| | - Nicolas Barnich
- UMR Inserm 1071, USC-INRAE 2018, M2iSH, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Julien Delmas
- UMR Inserm 1071, USC-INRAE 2018, M2iSH, Université Clermont Auvergne, Clermont-Ferrand, France
- Laboratoire de Bactériologie, CHU Clermont-Ferrand, Clermont-Ferrand, France
| | - Richard Bonnet
- UMR Inserm 1071, USC-INRAE 2018, M2iSH, Université Clermont Auvergne, Clermont-Ferrand, France
- Laboratoire de Bactériologie, CHU Clermont-Ferrand, Clermont-Ferrand, France
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Krause M, Barth H, Schmidt H. Toxins of Locus of Enterocyte Effacement-Negative Shiga Toxin-Producing Escherichia coli. Toxins (Basel) 2018; 10:toxins10060241. [PMID: 29903982 PMCID: PMC6024878 DOI: 10.3390/toxins10060241] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/07/2018] [Accepted: 06/12/2018] [Indexed: 12/16/2022] Open
Abstract
Studies on Shiga toxin-producing Escherichia coli (STEC) typically examine and classify the virulence gene profiles based on genomic analyses. Among the screened strains, a subgroup of STEC which lacks the locus of enterocyte effacement (LEE) has frequently been identified. This raises the question about the level of pathogenicity of such strains. This review focuses on the advantages and disadvantages of the standard screening procedures in virulence profiling and summarizes the current knowledge concerning the function and regulation of toxins encoded by LEE-negative STEC. Although LEE-negative STEC usually come across as food isolates, which rarely cause infections in humans, some serotypes have been implicated in human diseases. In particular, the LEE-negative E. coli O104:H7 German outbreak strain from 2011 and the Australian O113:H21 strain isolated from a HUS patient attracted attention. Moreover, the LEE-negative STEC O113:H21 strain TS18/08 that was isolated from minced meat is remarkable in that it not only encodes multiple toxins, but in fact expresses three different toxins simultaneously. Their characterization contributes to understanding the virulence of the LEE-negative STEC.
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Affiliation(s)
- Maike Krause
- Department of Food Microbiology and Hygiene, Institute of Food Science and Biotechnology, Garbenstrasse 28, University of Hohenheim, 70599 Stuttgart, Germany.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | - Herbert Schmidt
- Department of Food Microbiology and Hygiene, Institute of Food Science and Biotechnology, Garbenstrasse 28, University of Hohenheim, 70599 Stuttgart, Germany.
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Draft Genome Sequences of Five Shiga Toxin-Producing Escherichia coli Isolates Harboring the New and Recently Described Subtilase Cytotoxin Allelic Variant subAB2-3. GENOME ANNOUNCEMENTS 2017; 5:5/8/e01582-16. [PMID: 28232433 PMCID: PMC5323612 DOI: 10.1128/genomea.01582-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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 subAB2-3. Based on the sequence data, primers were designed to identify and differentiate this variant.
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Subtilase cytotoxin-encoding subAB2 variants in verotoxin-producing Escherichia coli strains isolated from goats and sheep. Res Vet Sci 2016; 105:74-6. [DOI: 10.1016/j.rvsc.2016.01.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 12/28/2015] [Accepted: 01/19/2016] [Indexed: 01/13/2023]
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Son HM, Duc HM, Honjoh KI, Miyamoto T. Identification of the newly identified subtilase cytotoxin-encoding gene (subAB2-2) among clinical Shiga toxin-producing Escherichia coli isolates. Can J Microbiol 2015; 61:990-4. [DOI: 10.1139/cjm-2015-0519] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Subtilase cytotoxin (SubAB) is an important virulence factor of eae-negative Shiga toxin-producing Escherichia coli (STEC). Three variants of SubAB-encoding genes have been reported in the literature; however, the newly described subAB variant (subAB2-2) was found only in STEC strains from deer meat, sheep, and some wild animals. In this study, subAB variants were detected by PCR and DNA sequencing in 5 out of 12 (41.6%) eae-negative STEC strains isolated from patients. Most subAB-positive STEC strains (80%) harbored the subAB1 gene. The subAB2-2 gene was detected for the first time in the clinical STEC O128:H2 strain. Other virulence genes including stx1a, stx1c, stx2b, ehxA, and tia were also detected in this strain. The DNA sequence analyses of the subAB1 and subAB2-2 genes of the clinical STEC strains showed 99% and 100% identity to those of the reference strains 98NK2 and LM27558stx2, respectively. This is the first report on the detection of the subAB2-2 gene in a clinical STEC isolate.
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Affiliation(s)
- Hoang Minh Son
- Laboratory of Food Hygienic Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
- Laboratory of Food Hygienic Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Hoang Minh Duc
- Laboratory of Food Hygienic Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
- Laboratory of Food Hygienic Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Ken-ichi Honjoh
- Laboratory of Food Hygienic Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
- Laboratory of Food Hygienic Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Takahisa Miyamoto
- Laboratory of Food Hygienic Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
- Laboratory of Food Hygienic Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
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Cytotoxic and apoptotic effects of recombinant subtilase cytotoxin variants of shiga toxin-producing Escherichia coli. Infect Immun 2015; 83:2338-49. [PMID: 25824835 DOI: 10.1128/iai.00231-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 03/20/2015] [Indexed: 12/24/2022] Open
Abstract
In this study, the cytotoxicity of the recently described subtilase variant SubAB2-2 of Shiga toxin-producing Escherichia coli was determined and compared to the plasmid-encoded SubAB1 and the chromosome-encoded SubAB2-1 variant. 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 SubA1 exhibited cytotoxic effects in the absence of the respective B1 subunit. A more detailed investigation in the human HeLa cell line revealed that SubA1 alone induced apoptosis, while the B1 subunit alone did not induce cell death.
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Nüesch-Inderbinen MT, Funk J, Cernela N, Tasara T, Klumpp J, Schmidt H, Stephan R. Prevalence of subtilase cytotoxin-encoding subAB variants among Shiga toxin-producing Escherichia coli strains isolated from wild ruminants and sheep differs from that of cattle and pigs and is predominated by the new allelic variant subAB2-2. Int J Med Microbiol 2015; 305:124-8. [DOI: 10.1016/j.ijmm.2014.11.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 10/20/2014] [Accepted: 11/12/2014] [Indexed: 01/01/2023] Open
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Miko A, Rivas M, Bentancor A, Delannoy S, Fach P, Beutin L. Emerging types of Shiga toxin-producing E. coli (STEC) O178 present in cattle, deer, and humans from Argentina and Germany. Front Cell Infect Microbiol 2014; 4:78. [PMID: 24987616 PMCID: PMC4060028 DOI: 10.3389/fcimb.2014.00078] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 05/26/2014] [Indexed: 11/18/2022] Open
Abstract
More than 400 serotypes of Shiga toxin-producing Escherichia coli (STEC) have been implicated in outbreaks and sporadic human diseases. In recent years STEC strains belonging to serogroup O178 have been commonly isolated from cattle and food of bovine origin in South America and Europe. In order to explore the significance of these STEC strains as potential human pathogens, 74 German and Argentinean E. coli O178 strains from animals, food and humans were characterized phenotypically and investigated for their serotypes, stx-genotypes and 43 virulence-associated markers by a real-time PCR-microarray. The majority (n = 66) of the O178 strains belonged to serotype O178:H19. The remaining strains divided into O178:H7 (n = 6), O178:H10 (n = 1), and O178:H16 (n = 1). STEC O178:H19 strains were mainly isolated from cattle and food of bovine origin, but one strain was from a patient with hemolytic uremic syndrome (HUS). Genotyping of the STEC O178:H19 strains by pulsed-field gel electrophoresis revealed two major clusters of genetically highly related strains which differ in their stx-genotypes and non-Stx putative virulence traits, including adhesins, toxins, and serine-proteases. Cluster A-strains including the HUS-strain (n = 35) carried genes associated with severe disease in humans (stx2a, stx2d, ehxA, saa, subAB1, lpfAO113 , terE combined with stx1a, espP, iha). Cluster B-strains (n = 26) showed a limited repertoire of virulence genes (stx2c, pagC, lpfAO113 , espP, iha). Among O178:H7 strains isolated from deer meat and patients with uncomplicated disease a new STEC variant was detected that is associated with the genotype stx1c/stx2b/ehxA/subAB2/espI/[terE]/espP/iha. None of the STEC O178 strains was positive for locus of enterocyte effacement (LEE)- and nle-genes. Results indicate that STEC O178:H19 strains belong to the growing group of LEE-negative STEC that should be considered with respect to their potential to cause diseases in humans.
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Affiliation(s)
- Angelika Miko
- Division of Microbial Toxins, National Reference Laboratory for Escherichia coli, Federal Institute for Risk Assessment (BfR)Berlin, Germany
| | - Marta Rivas
- Servicio Fisiopatogenia, Departamento de Bacteriología, Instituto Nacional de Enfermedades Infecciosas-ANLIS “Dr. Carlos G. Malbrán”Buenos Aires, Argentina
| | - Adriana Bentancor
- Cátedra de Microbiología, Facultad de Ciencias Veterinarias, Universidad de Buenos AiresBuenos Aires, Argentina
| | - Sabine Delannoy
- Food Safety Laboratory, French Agency for Food, Environmental and Occupational Health (Anses)Maisons-Alfort, France
| | - Patrick Fach
- Food Safety Laboratory, French Agency for Food, Environmental and Occupational Health (Anses)Maisons-Alfort, France
| | - Lothar Beutin
- Division of Microbial Toxins, National Reference Laboratory for Escherichia coli, Federal Institute for Risk Assessment (BfR)Berlin, Germany
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Sánchez S, Díaz-Sánchez S, Martínez R, Llorente MT, Herrera-León S, Vidal D. The new allelic variant of the subtilase cytotoxin (subAB2) is common among Shiga toxin-producing Escherichia coli strains from large game animals and their meat and meat products. Vet Microbiol 2013; 166:645-9. [PMID: 23880308 DOI: 10.1016/j.vetmic.2013.06.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/19/2013] [Accepted: 06/24/2013] [Indexed: 10/26/2022]
Abstract
Subtilase cytotoxin (SubAB) is an AB5 toxin produced by Shiga toxin (Stx)-producing Escherichia coli (STEC) strains usually lacking the eae gene product intimin. Two allelic variants of SubAB encoding genes have been described: subAB1, located on a plasmid, and subAB2, located on a pathogenicity island (PAI) together with tia gene. While subAB1 has been reported to be more frequent among bovine strains, subAB2 has been mainly associated with strains from small ruminants. We investigated the presence of the two variants of subAB among 59 eae-negative STEC from large game animals (deer and wild boar) and their meat and meat products in order to assess the role of other species in the epidemiology of subAB-positive, eae-negative STEC. For this approach, the strains were PCR-screened for the presence of subAB, including the specific detection of both allelic variants, for the presence of saa, tia and sab, and for stx subtyping. Overall, subAB genes were detected in 71.2% of the strains: 84.1% of the strains from deer and 33.3% of the strains from wild boar. Most of them (97.6%) possessed subAB2 and most of these subAB2-positive strains (92.7%) were also positive for tia and negative for saa, suggesting the presence of the subAB2-harbouring PAI. Subtype stx2b was present in most of the strains (67.8%) and a statistically significant association could be established between subAB2 and stx2b. Our results suggest that large game animals, mainly deer, may represent an important animal reservoir of subAB2-positive, eae-negative STEC, and also highlight the risk of human infection posed by the consumption of large game meat and meat products.
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Affiliation(s)
- Sergio Sánchez
- Unidad de Enterobacterias, Servicio de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Madrid, Spain.
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Pereira MDGC, Byrne BA, Nguyen TB, Lewis DJ, Atwill ER. The occurrence of subtilase-cytotoxin-encoding genes in environmental Escherichia coli isolated from a Northern California estuary. Can J Microbiol 2013; 59:437-41. [DOI: 10.1139/cjm-2012-0606] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The presence of subtilase-cytotoxin-encoding genes was determined in 397 environmental Escherichia coli strains isolated from water, suspended solids, and sediments sampled from different hydrological and environmental conditions in a California estuary. A total of 7 strains (1.76%) were found to harbor subtilase-cytotoxin-encoding genes. Using primers targeting subA only, we generated PCR amplicons from 2 strains; while using primers targeting the 3′ end of SubA downstream to the 5′ end of SubB, amplicons of 232 bp were generated from 5 additional strains. The 556 bp subA sequences were almost identical to that in the subtilase-cytotoxin-positive strain ED 591 (98%), while subAB sequences of 2 non-Shiga-toxigenic strains revealed 100% similarity with the Shiga-toxigenic E. coli O113:H21 strain 98NK2 that was isolated from an outbreak of hemolytic uremic syndrome. Additionally, the serogroup O113:H21 was present in this collection of environmental E. coli, and it was found to harbor stx2d, hra1 that encodes the heat resistant agglutinin 1, and a subAB sequence similar to that in the non-Shiga-toxigenic E. coli subtilase cytotoxin strain ED 591. To further understand potential health risks posed by strains encoding SubAB, future epidemiological studies should consider screening isolates for subAB regardless of the presence of Shiga-toxin-encoding genes.
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Affiliation(s)
- Maria das Graças C. Pereira
- Department of Population Health and Reproduction, School of Veterinary Medicine, 2012 Haring Hall, University of California, Davis, CA 95616, USA
| | - Barbara A. Byrne
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, 4206 VM3A, University of California, Davis, CA 95616, USA
| | - Trân B.H. Nguyen
- Department of Population Health and Reproduction, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, University of California, Davis, CA 95616, USA
| | - David J. Lewis
- University of California Cooperative Extension - Marin, 1682 Novato Boulevard, Suite 150B, Novato, CA 94947, USA
| | - E. Robert Atwill
- Western Institute for Food Safety and Security, 1089 Veterinary Medicine Drive, University of California, Davis, CA 95616, USA
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Michelacci V, Tozzoli R, Caprioli A, Martínez R, Scheutz F, Grande L, Sánchez S, Morabito S. A new pathogenicity island carrying an allelic variant of the Subtilase cytotoxin is common among Shiga toxin producing Escherichia coli of human and ovine origin. Clin Microbiol Infect 2013; 19:E149-56. [PMID: 23331629 DOI: 10.1111/1469-0691.12122] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 11/30/2012] [Accepted: 12/02/2012] [Indexed: 11/26/2022]
Abstract
Subtilase (SubAB) is a cytotoxin elaborated by some Shiga Toxin (Stx)-producing Escherichia coli (STEC) strains usually lacking the locus of enterocyte effacement (LEE). Two variants of SubAB coding genes have been described: subAB(1) , located on the plasmid of the STEC O113 98NK2 strain, and subAB(2) , located on a pathogenicity island (PAI) together with the tia gene, encoding an invasion determinant described in enterotoxigenic E. coli. In the present study, we determined the entire nucleotide sequence of the PAI containing the subAB(2) operon, termed Subtilase-Encoding PAI (SE-PAI), and identified its integration site in the pheV tRNA locus. In addition, a PCR strategy for discriminating the two subAB allelic variants was developed and used to investigate their presence in E. coli strains belonging to different pathotypes and in a large collection of LEE-negative STEC of human and ovine origin. The results confirmed that subAB genes are carried predominantly by STEC and showed their presence in 72% and 86% of the LEE-negative strains from human cases of diarrhoea and from healthy sheep respectively. Most of the subAB-positive strains (98%) identified possessed the subAB(2) allelic variant and were also positive for tia, suggesting the presence of SE-PAI. Altogether, our observations indicate that subAB(2) is the prevalent SubAB-coding operon in LEE-negative STEC circulating in European countries, and that sheep may represent an important reservoir for human infections with these strains. Further studies are needed to assess the role of tia and/or other genes carried by SE-PAI in the colonization of the host intestinal mucosa.
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Affiliation(s)
- V Michelacci
- European Reference Laboratory for Escherichia coli, Istituto Superiore di Sanità, Dipartimento di Sanità Pubblica Veterinaria e Sicurezza Alimentare, Rome, Italy
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13
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Subtilase cytotoxin encoding genes are present in human, sheep and deer intimin-negative, Shiga toxin-producing Escherichia coli O128:H2. Vet Microbiol 2012; 159:531-5. [DOI: 10.1016/j.vetmic.2012.04.036] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 04/25/2012] [Accepted: 04/27/2012] [Indexed: 01/20/2023]
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