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Scheutz F, Nielsen CH, von Mentzer A. Construction of the ETECFinder database for the characterization of enterotoxigenic Escherichia coli (ETEC) and revision of the VirulenceFinder web tool at the CGE website. J Clin Microbiol 2024; 62:e0057023. [PMID: 38656142 PMCID: PMC11237473 DOI: 10.1128/jcm.00570-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 03/05/2024] [Indexed: 04/26/2024] Open
Abstract
The identification of pathogens is essential for effective surveillance and outbreak detection, which lately has been facilitated by the decreasing cost of whole-genome sequencing (WGS). However, extracting relevant virulence genes from WGS data remains a challenge. In this study, we developed a web-based tool to predict virulence-associated genes in enterotoxigenic Escherichia coli (ETEC), which is a major concern for human and animal health. The database includes genes encoding the heat-labile toxin (LT) (eltA and eltB), heat-stable toxin (ST) (est), colonization factors CS1 through 30, F4, F5, F6, F17, F18, and F41, as well as toxigenic invasion and adherence loci (tia, tibAC, etpBAC, eatA, yghJ, and tleA). To construct the database, we revised the existing ETEC nomenclature and used the VirulenceFinder webtool at the CGE website [VirulenceFinder 2.0 (dtu.dk)]. The database was tested on 1,083 preassembled ETEC genomes, two BioProjects (PRJNA421191 with 305 and PRJNA416134 with 134 sequences), and the ETEC reference genome H10407. In total, 455 new virulence gene alleles were added, 50 alleles were replaced or renamed, and two were removed. Overall, our tool has the potential to greatly facilitate ETEC identification and improve the accuracy of WGS analysis. It can also help identify potential new virulence genes in ETEC. The revised nomenclature and expanded gene repertoire provide a better understanding of the genetic diversity of ETEC. Additionally, the user-friendly interface makes it accessible to users with limited bioinformatics experience. IMPORTANCE Detecting colonization factors in enterotoxigenic Escherichia coli (ETEC) is challenging due to their large number, heterogeneity, and lack of standardized tests. Therefore, it is important to include these ETEC-related genes in a more comprehensive VirulenceFinder database in order to obtain a more complete coverage of the virulence gene repertoire of pathogenic types of E. coli. ETEC vaccines are of great importance due to the severity of the infections, primarily in children. A tool such as this could assist in the surveillance of ETEC in order to determine the prevalence of relevant types in different parts of the world, allowing vaccine developers to target the most prevalent types and, thus, a more effective vaccine.
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Affiliation(s)
- Flemming Scheutz
- The International Escherichia and Klebsiella Centre, Statens Serum Institut, Copenhagen, Denmark
- Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
| | - Camilla Hald Nielsen
- The International Escherichia and Klebsiella Centre, Statens Serum Institut, Copenhagen, Denmark
- Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
| | - Astrid von Mentzer
- Department of Microbiology and Immunology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Xu C, She Y, Fu F, Xu C. Production of a new tetravalent vaccine targeting fimbriae and enterotoxin of enterotoxigenic Escherichia coli. CANADIAN JOURNAL OF VETERINARY RESEARCH = REVUE CANADIENNE DE RECHERCHE VETERINAIRE 2024; 88:38-44. [PMID: 38595949 PMCID: PMC11000427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 11/22/2023] [Indexed: 04/11/2024]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is an important type of pathogenic bacteria that causes diarrhea in pigs. The objective of this study was to prepare a novel tetravalent vaccine to effectively prevent piglet diarrhea caused by E. coli. In order to realize the production of K88ac-K99-ST1-LTB tetravalent inactivated vaccine, the biological characteristics, stability, preservation conditions, and safety of the recombinant strain BL21(DE3) (pXKKSL4) were studied, and the vaccine efficacy and minimum immune dose were measured. The results indicated that the biological characteristics, target protein expression, and immunogenicity of the 1st to 10th generations of the strain were stable. Therefore, the basic seed generation was preliminarily set as the 1st to 10th generations. The results of the efficacy tests showed that the immune protection rate could reach 90% with 1 minimum lethal dose (MLD) virulent strain attack in mice. The immunogenicity was stable, and the minimum immune dose was 0.1 mL per mouse. Our research showed that the genetically engineered vaccine developed in this way could prevent piglet diarrhea caused by enterotoxigenic E. coli through adhesin and enterotoxin. In order to realize industrial production of the vaccine as soon as possible, we conducted immunological tests and production process research on the constructed K88ac-K99-ST1-LTB tetravalent inactivated vaccine. The results of this study provide scientific experimental data for the commercial production of vaccines and lay a solid foundation for their industrial production.
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Affiliation(s)
- ChongLi Xu
- College of Medical Technology, Chongqing Medical and Pharmaceutical College, 82 Daxuecheng Road, Chongqing 401331, PR China (Xu, She, Fu); School of Biology and Agriculture, Shaoguan University, Shaoguan 512005, PR China (Xu)
| | - Yuhan She
- College of Medical Technology, Chongqing Medical and Pharmaceutical College, 82 Daxuecheng Road, Chongqing 401331, PR China (Xu, She, Fu); School of Biology and Agriculture, Shaoguan University, Shaoguan 512005, PR China (Xu)
| | - Fengyang Fu
- College of Medical Technology, Chongqing Medical and Pharmaceutical College, 82 Daxuecheng Road, Chongqing 401331, PR China (Xu, She, Fu); School of Biology and Agriculture, Shaoguan University, Shaoguan 512005, PR China (Xu)
| | - ChongBo Xu
- College of Medical Technology, Chongqing Medical and Pharmaceutical College, 82 Daxuecheng Road, Chongqing 401331, PR China (Xu, She, Fu); School of Biology and Agriculture, Shaoguan University, Shaoguan 512005, PR China (Xu)
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3
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Hu J, Li J, Huang X, Xia J, Cui M, Huang Y, Wen Y, Xie Y, Zhao Q, Cao S, Zou L, Han X. Genomic traits of multidrug resistant enterotoxigenic Escherichia coli isolates from diarrheic pigs. Front Microbiol 2023; 14:1244026. [PMID: 37601351 PMCID: PMC10434507 DOI: 10.3389/fmicb.2023.1244026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 07/17/2023] [Indexed: 08/22/2023] Open
Abstract
Diarrhea caused by enterotoxigenic Escherichia coli (ETEC) infections poses a significant challenge in global pig farming. To address this issue, the study was conducted to identify and characterize 19 ETEC isolates from fecal samples of diarrheic pigs sourced from large-scale farms in Sichuan Province, China. Whole-genome sequencing and bioinformatic analysis were utilized for identification and characterization. The isolates exhibited substantial resistance to cefotaxime, ceftriaxone, chloramphenicol, ciprofloxacin, gentamicin, ampicillin, tetracycline, florfenicol, and sulfadiazine, but were highly susceptible to amikacin, imipenem, and cefoxitin. Genetic diversity among the isolates was observed, with serotypes O22:H10, O163orOX21:H4, and O105:H8 being dominant. Further analysis revealed 53 resistance genes and 13 categories of 195 virulence factors. Of concern was the presence of tet(X4) in some isolates, indicating potential public health risks. The ETEC isolates demonstrated the ability to produce either heat-stable enterotoxin (ST) alone or both heat-labile enterotoxin (LT) and ST simultaneously, involving various virulence genes. Notably, STa were linked to human disease. Additionally, the presence of 4 hybrid ETEC/STEC isolates harboring Shiga-like toxin-related virulence factors, namely stx2a, stx2b, and stx2e-ONT-2771, was identified. IncF plasmids carrying multiple antimicrobial resistance genes were prevalent, and a hybrid ETEC/STEC plasmid was detected, highlighting the role of plasmids in hybrid pathotype emergence. These findings emphasized the multidrug resistance and pathogenicity of porcine-origin ETEC strains and the potential risk of epidemics through horizontal transmission of drug resistance, which is crucial for effective control strategies and interventions to mitigate the impact on animal and human health.
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Affiliation(s)
- Jiameng Hu
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Junlin Li
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xiaobo Huang
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
| | - Jing Xia
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
| | - Min Cui
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
| | - Yong Huang
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
| | - Yiping Wen
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
| | - Yue Xie
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
| | - Qin Zhao
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
| | - Sanjie Cao
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
| | - Likou Zou
- College of Resources, Sichuan Agricultural University, Chengdu, China
| | - Xinfeng Han
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
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Kartsev NN, Detusheva EV, Kalmantaeva OV, Korobova OV, Gerasimov VN, Kombarova TI, Borzilov AI, Fursova NK, Vereshchagin AN, Svetoch EA. Hetero-Pathogenic O181:H4 EAHEC Strain of Sequence Type ST678 Associated with Hemolytic-Uremic Syndrome in Schoolchildren in Russia. Microorganisms 2023; 11:1771. [PMID: 37512943 PMCID: PMC10383572 DOI: 10.3390/microorganisms11071771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/04/2023] [Accepted: 07/05/2023] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND In the last decade, the importance of hetero-pathogenic enteroaggregative Shiga-toxin-producing E. coli for public health has increased. Recently, we described the genetic background of the EAHEC O181:H4 strain of ST678 carrying the stx2 gene in prophage and five plasmids, including the plasmid-carrying aggR and aaiC genes. Here, we present the morphological and enzymatic characteristics of this strain, as well as susceptibility to antimicrobials, biofilm formation, etc. Methods: Bacterial morphology was studied using an electron microscope. Susceptibility to antimicrobials was determined using the microdilution method. Cytotoxicity was estimated in Vero cells. Virulence was studied on mice. RESULTS The morphological and enzymatic properties of the hetero-pathogenic EAHEC strain were typical for E. coli; electron microscopy revealed the specific flagella. The strain was susceptible to most antibiotics and disinfectants but resistant to ampicillin and ciprofloxacin and showed a high degree of biofilm formation. Cytotoxicity towards Vero cells was estimated as 80%. CONCLUSIONS The emergence of a new O181:H4 EAHEC strain poses a potential threat to humans because of the virulence potential that must be taken into account in the epidemiological analysis of outbreaks and sporadic cases of foodborne infections associated with hemolytic-uremic syndrome.
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Affiliation(s)
- Nikolay N Kartsev
- Department of Molecular Microbiology, State Research Center for Applied Microbiology and Biotechnology, Territory "Kvartal A", 142279 Obolensk, Russia
| | - Elena V Detusheva
- Department of Molecular Microbiology, State Research Center for Applied Microbiology and Biotechnology, Territory "Kvartal A", 142279 Obolensk, Russia
| | - Olga V Kalmantaeva
- Laboratory of Molecular Biology, State Research Center for Applied Microbiology and Biotechnology, Territory "Kvartal A", 142279 Obolensk, Russia
| | - Olga V Korobova
- Laboratory of Biological Trials, State Research Center for Applied Microbiology and Biotechnology, Territory "Kvartal A", 142279 Obolensk, Russia
| | - Vladimir N Gerasimov
- Department of Disinfectology, State Research Center for Applied Microbiology and Biotechnology, Territory "Kvartal A", 142279 Obolensk, Russia
| | - Tatiana I Kombarova
- Laboratory of Biological Trials, State Research Center for Applied Microbiology and Biotechnology, Territory "Kvartal A", 142279 Obolensk, Russia
| | - Aleksander I Borzilov
- Laboratory of Biological Trials, State Research Center for Applied Microbiology and Biotechnology, Territory "Kvartal A", 142279 Obolensk, Russia
| | - Nadezhda K Fursova
- Department of Molecular Microbiology, State Research Center for Applied Microbiology and Biotechnology, Territory "Kvartal A", 142279 Obolensk, Russia
| | | | - Edward A Svetoch
- Department of Molecular Microbiology, State Research Center for Applied Microbiology and Biotechnology, Territory "Kvartal A", 142279 Obolensk, Russia
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Okuno M, Arimizu Y, Miyahara S, Wakabayashi Y, Gotoh Y, Yoshino S, Harada T, Seto K, Yamamoto T, Nakamura K, Hayashi T, Ogura Y. Escherichia cryptic clade I is an emerging source of human intestinal pathogens. BMC Biol 2023; 21:81. [PMID: 37055811 PMCID: PMC10100065 DOI: 10.1186/s12915-023-01584-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 03/30/2023] [Indexed: 04/15/2023] Open
Abstract
BACKGROUND Within the genus Escherichia, several monophyletic clades other than the traditionally defined species have been identified. Of these, cryptic clade I (C-I) appears to represent a subspecies of E. coli, but due to the difficulty in distinguishing it from E. coli sensu stricto, the population structure and virulence potential of C-I are unclear. RESULTS We defined a set of true C-I strains (n = 465), including a Shiga toxin 2a (Stx2a)-producing isolate from a patient with bloody diarrhoea identified by the retrospective analyses using a C-I-specific detection system. Through genomic analysis of 804 isolates from the cryptic clades, including these C-I strains, we revealed their global population structures and the marked accumulation of virulence genes and antimicrobial resistance genes in C-I. In particular, half of the C-I strains contained hallmark virulence genes of Stx-producing E. coli (STEC) and/or enterotoxigenic E. coli (ETEC). We also found the host-specific distributions of virulence genes, which suggests bovines as the potential source of human infections caused by STEC- and STEC/ETEC hybrid-type C-I strains, as is known in STEC. CONCLUSIONS Our findings demonstrate the emergence of human intestinal pathogens in C-I lineage. To better understand the features of C-I strains and their infections, extensive surveillance and larger population studies of C-I strains are needed. The C-I-specific detection system developed in this study will be a powerful tool for screening and identifying C-I strains.
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Affiliation(s)
- Miki Okuno
- Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Yoko Arimizu
- Department of Bacteriology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Infectious Disease, National Hospital Organization Kyushu Medical Center, Fukuoka, 810-0065, Japan
| | - Seina Miyahara
- Department of Microbiology, Miyazaki Prefectural Institute for Public Health and Environment, Miyazaki, 889-2155, Japan
| | - Yuki Wakabayashi
- Division of Microbiology, Osaka Institute of Public Health, Osaka, 537-0025, Japan
| | - Yasuhiro Gotoh
- Department of Bacteriology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Shuji Yoshino
- Department of Microbiology, Miyazaki Prefectural Institute for Public Health and Environment, Miyazaki, 889-2155, Japan
| | - Tetsuya Harada
- Division of Microbiology, Osaka Institute of Public Health, Osaka, 537-0025, Japan
| | - Kazuko Seto
- Division of Planning, Osaka Institute of Public Health, Osaka, 537-0025, Japan
| | - Takeshi Yamamoto
- Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Keiji Nakamura
- Department of Bacteriology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Tetsuya Hayashi
- Department of Bacteriology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Yoshitoshi Ogura
- Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan.
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Xu C, Peng K, She Y, Fu F, Shi Q, Lin Y, Xu C. Preparation of novel trivalent vaccine against enterotoxigenic Escherichia coli for preventing newborn piglet diarrhea. Am J Vet Res 2023; 84:ajvr.22.10.0183. [PMID: 36576801 DOI: 10.2460/ajvr.22.10.0183] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To develop a trivalent genetically engineered inactivated Escherichia coli vaccine (K88ac-3STa-LTB) that neutralizes the STa toxin by targeting fimbriae and entertoxins for the treatment of enterotoxigenic E coli. ANIMALS 18- to 22-g mice, rabbits, pregnant sows. PROCEDURES Using PCR, the K88ac gene and LTB gene were cloned separately from the template C83902 plasmid. At the same time, the 3 STa mutant genes were also amplified by using the gene-directed mutation technology. Immune protection experiments were performed, and the minimum immune dose was determined in mice and pregnant sows. RESULTS The ELISA test could be recognized by the STa, LTB, and K88ac antibodies. Intragastric administration in the suckling mouse confirmed that the protein had lost the toxicity of the natural STa enterotoxin. The results of the immune experiments showed that K88ac-3STa-LTB protein could stimulate rabbits to produce serum antibodies and neutralize the toxicity of natural STa enterotoxin. The efficacy test of the K88ac-3STa-LTB-inactivated vaccine showed that the immune protection rate of the newborn piglets could reach 85% on the first day after suckling. At the same time, it was determined that the minimum immunization doses for mice and pregnant sows were 0.2 and 2.5 mL, respectively. CLINICAL RELEVANCE This research indicates that the K88ac-3STa-LTB trivalent genetically engineered inactivated vaccine provides a broad immune spectrum for E coli diarrhea in newborn piglets and prepares a new genetically engineered vaccine candidate strain for prevention of E coli diarrhea in piglets.
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Affiliation(s)
- ChongLi Xu
- College of Medical Technology, Chongqing Medical and Pharmaceutical College, Chongqing, People's Republic of China
| | - Kun Peng
- College of Medical Technology, Chongqing Medical and Pharmaceutical College, Chongqing, People's Republic of China
| | - Yuhan She
- College of Medical Technology, Chongqing Medical and Pharmaceutical College, Chongqing, People's Republic of China
| | - Fengyang Fu
- College of Medical Technology, Chongqing Medical and Pharmaceutical College, Chongqing, People's Republic of China
| | - Qinhong Shi
- College of Medical Technology, Chongqing Medical and Pharmaceutical College, Chongqing, People's Republic of China
| | - Yimin Lin
- Chongqing Key Laboratory of Translational Research for Cancer Metastasis and Individualized Treatment, Chongqing University Cancer Hospital, Chongqing, People's Republic of China
| | - ChongBo Xu
- Henry Fok College of Biology and Agriculture, Shaoguan University, Shaoguan, People's Republic of China
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Geurtsen J, de Been M, Weerdenburg E, Zomer A, McNally A, Poolman J. Genomics and pathotypes of the many faces of Escherichia coli. FEMS Microbiol Rev 2022; 46:6617594. [PMID: 35749579 PMCID: PMC9629502 DOI: 10.1093/femsre/fuac031] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 06/22/2022] [Indexed: 01/09/2023] Open
Abstract
Escherichia coli is the most researched microbial organism in the world. Its varied impact on human health, consisting of commensalism, gastrointestinal disease, or extraintestinal pathologies, has generated a separation of the species into at least eleven pathotypes (also known as pathovars). These are broadly split into two groups, intestinal pathogenic E. coli (InPEC) and extraintestinal pathogenic E. coli (ExPEC). However, components of E. coli's infinite open accessory genome are horizontally transferred with substantial frequency, creating pathogenic hybrid strains that defy a clear pathotype designation. Here, we take a birds-eye view of the E. coli species, characterizing it from historical, clinical, and genetic perspectives. We examine the wide spectrum of human disease caused by E. coli, the genome content of the bacterium, and its propensity to acquire, exchange, and maintain antibiotic resistance genes and virulence traits. Our portrayal of the species also discusses elements that have shaped its overall population structure and summarizes the current state of vaccine development targeted at the most frequent E. coli pathovars. In our conclusions, we advocate streamlining efforts for clinical reporting of ExPEC, and emphasize the pathogenic potential that exists throughout the entire species.
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Affiliation(s)
- Jeroen Geurtsen
- Janssen Vaccines and Prevention B.V., 2333 Leiden, the Netherlands
| | - Mark de Been
- Janssen Vaccines and Prevention B.V., 2333 Leiden, the Netherlands
| | | | - Aldert Zomer
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 Utrecht, the Netherlands
| | - Alan McNally
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, B15 2TT Birmingham, United Kingdom
| | - Jan Poolman
- Janssen Vaccines and Prevention B.V., 2333 Leiden, the Netherlands
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Perrat A, Branchu P, Decors A, Turci S, Bayon-Auboyer MH, Petit G, Grosbois V, Brugère H, Auvray F, Oswald E. Wild Boars as Reservoir of Highly Virulent Clone of Hybrid Shiga Toxigenic and Enterotoxigenic Escherichia coli Responsible for Edema Disease, France. Emerg Infect Dis 2022; 28:382-393. [PMID: 35075992 PMCID: PMC8798679 DOI: 10.3201/eid2802.211491] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Edema disease is an often fatal enterotoxemia caused by specific strains of Shiga toxin–producing Escherichia coli (STEC) that affect primarily healthy, rapidly growing nursery pigs. Recently, outbreaks of edema disease have also emerged in France in wild boars. Analysis of STEC strains isolated from wild boars during 2013–2019 showed that they belonged to the serotype O139:H1 and were positive for both Stx2e and F18 fimbriae. However, in contrast to classical STEC O139:H1 strains circulating in pigs, they also possessed enterotoxin genes sta1 and stb, typical of enterotoxigenic E. coli. In addition, the strains contained a unique accessory genome composition and did not harbor antimicrobial-resistance genes, in contrast to domestic pig isolates. These data thus reveal that the emergence of edema disease in wild boars was caused by atypical hybrid of STEC and enterotoxigenic E. coli O139:H1, which so far has been restricted to the wildlife environment.
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Bolukaoto JY, Singh A, Alfinete N, Barnard TG. Occurrence of Hybrid Diarrhoeagenic Escherichia coli Associated with Multidrug Resistance in Environmental Water, Johannesburg, South Africa. Microorganisms 2021; 9:2163. [PMID: 34683484 PMCID: PMC8538365 DOI: 10.3390/microorganisms9102163] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/25/2021] [Accepted: 09/27/2021] [Indexed: 12/20/2022] Open
Abstract
This study was undertaken to determine the virulence and antibiotic resistance profiles of diarrhoeagenic Escherichia coli (DEC) in environmental waters of Johannesburg, South Africa. Samples were collected and cultured on selective media. An 11-plex PCR assay was used to differentiate five DEC, namely: enteroaggregative (EAEC), enterohaemorrhagic (EHEC), enteroinvasive (EIEC), enteropathogenic (EPEC) and enterotoxigenic (ETEC). The antibiotic resistance profile of isolates was determined using the VITEK®-2 automated system. The virulence profiles of 170 E. coli tested showed that 40% (68/170) were commensals and 60% (102/170) were pathogenic. EPEC had a prevalence of 19.2% (32/170), followed by ETEC 11.4% (19/170), EAEC 6% (10/170) and EHEC 3% (5/170). Hybrid DEC carrying a combination of simultaneously two and three pathogenic types was detected in twenty-eight and nine isolates, respectively. The antibiotic susceptibility testing showed isolates with multidrug resistance, including cefuroxime (100%), ceftazidime (86%), cefotaxime (81%) and cefepime (79%). This study highlighted the widespread occurrence of DEC and antibiotic resistance strains in the aquatic ecosystem of Johannesburg. The presence of hybrid pathotypes detected in this study is alarming and might lead to more severe diseases. There is a necessity to enhance surveillance in reducing the propagation of pathogenic and antibiotic-resistant strains in this area.
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Affiliation(s)
| | | | | | - Tobias G. Barnard
- Water and Health Research Centre, University of Johannesburg, Doornfontein 2092, South Africa; (J.Y.B.); (A.S.); (N.A.)
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McMAHON T, Bastian J, Alshawa I, Gill A. PCR Primers for Screening Food for Verotoxin-Producing Escherichia coli, Inclusive of Three vt1 and Seven vt2 Subtypes. J Food Prot 2021; 84:296-302. [PMID: 32977337 DOI: 10.4315/jfp-20-233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/21/2020] [Indexed: 11/11/2022]
Abstract
ABSTRACT Verotoxin-producing Escherichia coli (VTEC; also known as Shiga toxin-producing E. coli) is a significant cause of foodborne illnesses around the world. Due to the serological and genomic diversity of VTEC, methods of detection for VTEC in food samples require detection of verotoxin or its gene vt (also known as stx). The current taxonomy of vt identifies three vt1 (a, c, d) and seven vt2 (a to g) subtypes. PCR detection of vt is convenient and rapid, but protocols may not detect all currently identified variants or subtypes of vt. The Health Canada Compendium of Analytical Methods protocol for the analysis of food for VTEC is MFLP-52. MFLP-52 includes a VT Screening PCR that is used to determine the presumptive presence of VTEC by the detection of vt in food enrichments and to differentiate VTEC from other isolates. The VT Screening PCR was developed prior to the establishment of the current vt taxonomy. An evaluation of VT Screening PCR for detection of the 10 established vt subtypes was performed, and it was discovered that the method could not detect subtypes vt1d and vt2f. Additional primers and a modified protocol were developed, and the modified VT Screening PCR was tested against an inclusivity panel of 50 VTEC strains, including representatives of 10 vt subtypes, and an exclusivity panel of 30 vt-negative E. coli from various sources, to ensure specificity. The reliability of MFLP-52 with the modified VT Screening PCR was assessed by analysis of four priority food matrices (ground beef, lettuce, cheese, and apple cider) inoculated with a VTEC strain at 2 to 5 CFU/25 g. The modified VT Screening PCR was determined to be able to detect all 10 vt subtypes and reliably detect the presence of VTEC in all tested food enrichments. HIGHLIGHTS
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Affiliation(s)
- Tanis McMAHON
- Health Canada, Bureau of Microbial Hazards, 251 Sir Frederick Banting Driveway, Ottawa, Ontario, Canada K1A 0K9
| | - Jillian Bastian
- Health Canada, Bureau of Microbial Hazards, 251 Sir Frederick Banting Driveway, Ottawa, Ontario, Canada K1A 0K9
| | - Inas Alshawa
- Health Canada, Bureau of Microbial Hazards, 251 Sir Frederick Banting Driveway, Ottawa, Ontario, Canada K1A 0K9
| | - Alexander Gill
- Health Canada, Bureau of Microbial Hazards, 251 Sir Frederick Banting Driveway, Ottawa, Ontario, Canada K1A 0K9.,(ORCID: https://orcid.org/0000-0003-2380-2148 [A.G.])
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11
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García A, Fox JG. A One Health Perspective for Defining and Deciphering Escherichia coli Pathogenic Potential in Multiple Hosts. Comp Med 2021; 71:3-45. [PMID: 33419487 PMCID: PMC7898170 DOI: 10.30802/aalas-cm-20-000054] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/17/2020] [Accepted: 09/19/2020] [Indexed: 11/05/2022]
Abstract
E. coli is one of the most common species of bacteria colonizing humans and animals. The singularity of E. coli 's genus and species underestimates its multifaceted nature, which is represented by different strains, each with different combinations of distinct virulence factors. In fact, several E. coli pathotypes, or hybrid strains, may be associated with both subclinical infection and a range of clinical conditions, including enteric, urinary, and systemic infections. E. coli may also express DNA-damaging toxins that could impact cancer development. This review summarizes the different E. coli pathotypes in the context of their history, hosts, clinical signs, epidemiology, and control. The pathotypic characterization of E. coli in the context of disease in different animals, including humans, provides comparative and One Health perspectives that will guide future clinical and research investigations of E. coli infections.
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Key Words
- aa, aggregative adherence
- a/e, attaching and effacing
- aepec, atypical epec
- afa, afimbrial adhesin
- aida-i, adhesin involved in diffuse adherence
- aiec, adherent invasive e. coli
- apec, avian pathogenic e. coli
- atcc, american type culture collection
- bfp, bundle-forming pilus
- cd, crohn disease
- cdt, cytolethal distending toxin gene
- clb, colibactin
- cnf, cytotoxic necrotizing factor
- cs, coli surface (antigens)
- daec, diffusely adhering e. coli
- db, dutch belted
- eae, e. coli attaching and effacing gene
- eaec, enteroaggregative e. coli
- eaf, epec adherence factor (plasmid)
- eahec, entero-aggregative-hemorrhagic e. coli
- east-1, enteroaggregative e. coli heat-stable enterotoxin
- e. coli, escherichia coli
- ed, edema disease
- ehec, enterohemorrhagic e. coli
- eiec, enteroinvasive e. coli
- epec, enteropathogenic e. coli
- esbl, extended-spectrum β-lactamase
- esp, e. coli secreted protein
- etec, enterotoxigenic e. coli
- expec, extraintestinal pathogenic e. coli
- fyua, yersiniabactin receptor gene
- gi, gastrointestinal
- hly, hemolysin
- hus, hemolytic uremic syndrome
- ibd, inflammatory bowel disease
- la, localized adherence
- lee, locus of enterocyte effacement
- lpf, long polar fimbriae
- lt, heat-labile (enterotoxin)
- mlst, multilocus sequence typing
- ndm, new delhi metallo-β-lactamase
- nzw, new zealand white
- pap, pyelonephritis-associated pilus
- pks, polyketide synthase
- sfa, s fimbrial adhesin
- slt, shiga-like toxin
- st, heat-stable (enterotoxin)
- stec, stx-producing e. coli
- stx, shiga toxin
- tepec, typical epec
- upec, uropathogenic e. coli
- uti, urinary tract infection
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Affiliation(s)
- Alexis García
- Molecular Sciences Research Center, University of Puerto Rico, San Juan, Puerto Rico; Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts; Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts;,
| | - James G Fox
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts
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12
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Wang W, Zijlstra RT, Gänzle MG. Feeding Limosilactobacillus fermentum K9-2 and Lacticaseibacillus casei K9-1, or Limosilactobacillus reuteri TMW1.656 Reduces Pathogen Load in Weanling Pigs. Front Microbiol 2020; 11:608293. [PMID: 33391231 PMCID: PMC7773707 DOI: 10.3389/fmicb.2020.608293] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 11/23/2020] [Indexed: 01/04/2023] Open
Abstract
Applying probiotics to improve gut health and growth performance of pigs is considered an effective approach to reduce use of antimicrobial growth promoters in swine production. Understanding the properties of these probiotics is a prerequisite for the selection of probiotic strains for pigs. Host-adapted probiotic strains were suggested to exert probiotic effects by different mechanisms when compared to free-living or nomadic probiotic strains. This study assessed the effect of probiotic intervention with Limosilactobacillus reuteri TMW1.656, a host-adapted species producing the antimicrobial compound reutericyclin, its isogenic and reutericyclin-negative L. reuteri TMW1.656ΔrtcN, and with Limosilactobacillus fermentum and Lacticaseibacillus casei, two species with a nomadic lifestyle. Probiotic strains were supplemented to the post weaning diet in piglets by fermented feed or as freeze-dried cultures. The composition of fecal microbiota was determined by high throughput sequencing of 16S rRNA gene sequence tags; Enterotoxigenic Escherichia coli and Clostridium perfringens were quantified by qPCR targeting specific virulence factors. Inclusion of host-adapted L. reuteri effectively reduced ETEC abundance in swine intestine. In contrast, nomadic L. fermentum and L. casei did not show inhibitory effects on ETEC but reduced the abundance of Clostridium spp. In addition, the increasing abundance of Bacteriodetes after weaning was correlated to a reduction of ETEC abundance. Remarkably, the early colonization of piglets with ETEC was impacted by maternal-neonatal transmission; the pattern of virulence factors changed significantly over time after weaning. Probiotic intervention or the production of reutericyclin showed limited effect on the overall composition of commensal gut microbiota. In conclusion, the present study provided evidence that the lifestyle of lactobacilli is a relevant criterion for selection of probiotic cultures while the production of antimicrobial compounds has only minor effects.
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Affiliation(s)
| | | | - Michael G. Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
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13
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Khine NO, Lugsomya K, Kaewgun B, Honhanrob L, Pairojrit P, Jermprasert S, Prapasarakul N. Multidrug Resistance and Virulence Factors of Escherichia coli Harboring Plasmid-Mediated Colistin Resistance: mcr-1 and mcr-3 Genes in Contracted Pig Farms in Thailand. Front Vet Sci 2020; 7:582899. [PMID: 33240958 PMCID: PMC7683614 DOI: 10.3389/fvets.2020.582899] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 10/02/2020] [Indexed: 12/01/2022] Open
Abstract
The presence of the plasmid-mediated colistin resistance encoding mcr gene family in the Enterobacteriaceae is one of the crucial global concerns. The use of colistin in livestock rearing is believed to be the cause of mcr gene spreading and is of impact to public health. The objective of this research was to detect the frequency and virulent genes of mcr-positive Escherichia coli (MCRPE) in fecal samples from healthy pigs in a contract farming system across Thailand. A total of 696 pooled samples were derived from 80 farms, located in 49 provinces across six regions of Thailand. The colistin-resistant E. coli were identified by MALDI-TOF mass spectrometry and antimicrobial susceptibility testing by broth microdilution. The antibiogram was determined using an automated susceptibility machine, and the genetic characteristics were investigated for mcr-1–5 genes, phylogenetic group, replicon types, and virulent genes. In total, 31 of 696 samples were positive, with E. coli containing mcr-1 or combination of mcr-1 and mcr-3 with incidence of 4.45 and 0.43%. Phylogenetic groups A and B1 and the IncF and IncFIB replicon types were predominantly found in the MCRPE located in the central area, with multidrug-resistant traits against 3–14 types of antimicrobials. Additionally, 19 of 31 isolates identified as enterotoxigenic E. coli were with the stap and stb (enterotoxin-encoding genes). In conclusion, a low carriage rate of mcr-positive E. coli was detected in the large-scale farming of healthy pigs. The association between multidrug-resistant MCRPE and their pathogenic potential should be of concern.
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Affiliation(s)
- Nwai Oo Khine
- Department of Veterinary Microbiology, Faculty of Veterinary Sciences, Chulalongkorn University, Bangkok, Thailand.,The International Graduate Course of Veterinary Science and Technology, Chulalongkorn University, Bangkok, Thailand
| | - Kittitat Lugsomya
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, China
| | - Benjarong Kaewgun
- Department of Veterinary Microbiology, Faculty of Veterinary Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Lertrob Honhanrob
- Department of Veterinary Microbiology, Faculty of Veterinary Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Panupong Pairojrit
- Department of Veterinary Microbiology, Faculty of Veterinary Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Suthipat Jermprasert
- Department of Veterinary Microbiology, Faculty of Veterinary Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Nuvee Prapasarakul
- Department of Veterinary Microbiology, Faculty of Veterinary Sciences, Chulalongkorn University, Bangkok, Thailand.,Diagnosis and Monitoring of Animal Pathogen Research Unit (DMAP), Bangkok, Thailand
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14
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Harrison LM, Lacher DW, Mammel MK, Leonard SR. Comparative Transcriptomics of Shiga Toxin-Producing and Commensal Escherichia coli and Cytokine Responses in Colonic Epithelial Cell Culture Infections. Front Cell Infect Microbiol 2020; 10:575630. [PMID: 33194815 PMCID: PMC7649339 DOI: 10.3389/fcimb.2020.575630] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 10/07/2020] [Indexed: 12/12/2022] Open
Abstract
Ingestion of Shiga toxin-producing Escherichia coli (STEC) can result in a range of illness severity from asymptomatic to hemorrhagic colitis and death; thus risk assessment of STEC strains for human pathogenicity is important in the area of food safety. Illness severity depends in part on the combination of virulence genes carried in the genome, which can vary between strains even of identical serotype. To better understand how core genes are regulated differently among strains and to identify possible novel STEC virulence gene candidates that could be added to the risk assessment repertoire, we used comparative transcriptomics to investigate global gene expression differences between two STEC strains associated with severe illness and a commensal E. coli strain during in vitro intestinal epithelial cell (IEC) infections. Additionally, we compared a wide array of concomitant cytokine levels produced by the IECs. The cytokine expression levels were examined for a pattern representing STEC pathogenicity; however, while one STEC strain appeared to elicit a proinflammatory response, infection by the other strain produced a pattern comparable to the commensal E. coli. This result may be explained by the significant differences in gene content and expression observed between the STEC strains. RNA-Seq analysis revealed considerable disparity in expression of genes in the arginine and tryptophan biosynthesis/import pathways between the STEC strains and the commensal E. coli strain, highlighting the important role some amino acids play in STEC colonization and survival. Contrasting differential expression patterns were observed for genes involved in respiration among the three strains suggesting that metabolic diversity is a strategy utilized to compete with resident microflora for successful colonization. Similar temporal expression results for known and putative virulence genes were observed in the STEC strains, revealing strategies used for survival prior to and after initial adherence to IECs. Additionally, three genes encoding hypothetical proteins located in mobile genetic elements were, after interrogation of a large set of E. coli genomes, determined to likely represent novel STEC virulence factors.
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Affiliation(s)
- Lisa M Harrison
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, MD, United States
| | - David W Lacher
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, MD, United States
| | - Mark K Mammel
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, MD, United States
| | - Susan R Leonard
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, MD, United States
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15
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Santos ACDM, Santos FF, Silva RM, Gomes TAT. Diversity of Hybrid- and Hetero-Pathogenic Escherichia coli and Their Potential Implication in More Severe Diseases. Front Cell Infect Microbiol 2020; 10:339. [PMID: 32766163 PMCID: PMC7381148 DOI: 10.3389/fcimb.2020.00339] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 06/04/2020] [Indexed: 12/17/2022] Open
Abstract
Although extraintestinal pathogenic Escherichia coli (ExPEC) are designated by their isolation site and grouped based on the type of host and the disease they cause, most diarrheagenic E. coli (DEC) are subdivided into several pathotypes based on the presence of specific virulence traits directly related to disease development. This scenario of a well-categorized E. coli collapsed after the German outbreak of 2011, caused by one strain bearing the virulence factors of two different DEC pathotypes (enteroaggregative E. coli and Shiga toxin-producing E. coli). Since the outbreak, many studies have shown that this phenomenon is more frequent than previously realized. Therefore, the terms hybrid- and hetero-pathogenic E. coli have been coined to describe new combinations of virulence factors among the classic E. coli pathotypes. In this review, we provide an overview of these classifications and highlight the E. coli genomic plasticity that results in some mixed E. coli pathotypes displaying novel pathogenic strategies, which lead to a new symptomatology related to E. coli diseases. In addition, as the capacity for genome interrogation has grown in the last few years, it is clear that genes encoding some virulence factors, such as Shiga toxin, are found among different E. coli pathotypes to which they have not traditionally been associated, perhaps foreshowing their emergence in new and severe outbreaks caused by such hybrid strains. Therefore, further studies regarding hetero-pathogenic and hybrid-pathogenic E. coli isolates are necessary to better understand and control the spread of these pathogens.
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Affiliation(s)
- Ana Carolina de Mello Santos
- Disciplina de Microbiologia, Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Fernanda Fernandes Santos
- Disciplina de Microbiologia, Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Rosa Maria Silva
- Disciplina de Microbiologia, Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Tânia Aparecida Tardelli Gomes
- Disciplina de Microbiologia, Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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16
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Bai X, Zhang J, Ambikan A, Jernberg C, Ehricht R, Scheutz F, Xiong Y, Matussek A. Molecular Characterization and Comparative Genomics of Clinical Hybrid Shiga Toxin-Producing and Enterotoxigenic Escherichia coli (STEC/ETEC) Strains in Sweden. Sci Rep 2019; 9:5619. [PMID: 30948755 PMCID: PMC6449507 DOI: 10.1038/s41598-019-42122-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 03/21/2019] [Indexed: 12/21/2022] Open
Abstract
Hybrid E. coli pathotypes are representing emerging public health threats with enhanced virulence from different pathotypes. Hybrids of Shiga toxin-producing and enterotoxigenic E. coli (STEC/ETEC) have been reported to be associated with diarrheal disease and hemolytic uremic syndrome (HUS) in humans. Here, we identified and characterized four clinical STEC/ETEC hybrids from diarrheal patients with or without fever or abdominal pain and healthy contact in Sweden. Rare stx2 subtypes were present in STEC/ETEC hybrids. Stx2 production was detectable in stx2a and stx2e containing strains. Different copies of ETEC virulence marker, sta gene, were found in two hybrids. Three sta subtypes, namely, sta1, sta4 and sta5 were designated, with sta4 being predominant. The hybrids represented diverse and rare serotypes (O15:H16, O187:H28, O100:H30, and O136:H12). Genome-wide phylogeny revealed that these hybrids exhibited close relatedness with certain ETEC, STEC/ETEC hybrid and commensal E. coli strains, implying the potential acquisition of Stx-phages or/and ETEC virulence genes in the emergence of STEC/ETEC hybrids. Given the emergence and public health significance of hybrid pathotypes, a broader range of virulence markers should be considered in the E. coli pathotypes diagnostics, and targeted follow up of cases is suggested to better understand the hybrid infection.
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Affiliation(s)
- Xiangning Bai
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden.,State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Ji Zhang
- mEpiLab, New Zealand Food Safety Science & Research Centre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Massey, New Zealand
| | - Anoop Ambikan
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden
| | | | - Ralf Ehricht
- InfectoGnostics Research Campus e.V., Philosophenweg 7, Jena, Germany.,Leibniz Institute of Photonic Technology e.V. Jena (Leibniz-IPHT), Jena, Germany
| | - Flemming Scheutz
- The International Centre for Reference and Research on Escherichia and Klebsiella, Unit of Foodborne Bacteria and Typing, Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
| | - Yanwen Xiong
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Andreas Matussek
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden. .,Karolinska University Laboratory, Stockholm, Sweden. .,Department of Laboratory Medicine, Region Jönköping County, Jönköping, Sweden.
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17
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Brilhante M, Perreten V, Donà V. Multidrug resistance and multivirulence plasmids in enterotoxigenic and hybrid Shiga toxin-producing/enterotoxigenic Escherichia coli isolated from diarrheic pigs in Switzerland. Vet J 2018; 244:60-68. [PMID: 30825896 DOI: 10.1016/j.tvjl.2018.12.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 12/04/2018] [Accepted: 12/10/2018] [Indexed: 01/08/2023]
Abstract
Enterovirulent Escherichia coli infections cause significant losses in the pig industry. However, information about the structures of the virulence and multidrug resistance (MDR) plasmids harboured by these strains is sparse. In this study, we used whole-genome sequencing with PacBio and Illumina platforms to analyse the molecular features of the multidrug-resistant enterotoxigenic E. coli (ETEC) strain 14OD0056 and the multidrug-resistant hybrid Shiga toxin-producing/enterotoxigenic E. coli (STEC/ETEC) strain 15OD0495 isolated from diarrheic pigs in Switzerland. Strain 14OD0056 possessed three virulence plasmids similar to others previously found in ETEC strains, while 15OD0495 harboured a 119-kb multivirulence IncFII/IncX1 hybrid STEC/ETEC plasmid (p15ODTXV) that co-carried virulence genes of both ETEC and STEC pathotypes, confirming the key role of plasmids in the emergence of hybrid pathotypes. All resistance genes of 14OD0056 that conferred resistance to ampicillin (blaTEM-1b), gentamicin (aac(3)-IIa), kanamycin (aph(3')-Ia), sulfonamide (sul1 and sul2), streptomycin (aph(3″)-Ib, aph(6)-Id), tetracycline (tet(B)) and trimethoprim (dfrA1) were identified on a single 207-kb conjugative MDR plasmid of incompatibility group (Inc) IncHI1/IncFIA (p14ODMR). Strain 15OD0495 carried two antimicrobial resistance plasmids (p15ODAR and p15ODMR). The 99-kb IncI1 plasmid p15ODAR harboured only aminoglycoside resistance genes (aac(3)-IIa, aph(3″)-Ib, aph(6)-Id, aph(4)-Ia), whilst the 49-kb IncN MDR plasmid p15ODMR carried genes conferring resistance to ampicillin (blaTEM-1b), sulfonamide (sul2), streptomycin (aph(6)-Id), tetracycline (tet(A)) and trimethoprim (dfrA14). Filter mating assays showed that p14ODMR, p15ODMR and p15ODAR were conjugative at room temperature and 37°C. The co-localization of multiple resistance genes on MDR conjugative plasmids such as p14ODMR and p15ODMR poses the risk of simultaneous selection of several resistance traits during empirical treatment. Thus, preventive strategies and targeted therapy following antibiotic susceptibility testing should be encouraged to avoid further dissemination of such plasmids.
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Affiliation(s)
- M Brilhante
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland; Graduate School of Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - V Perreten
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
| | - V Donà
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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18
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Gioia-Di Chiacchio RM, Cunha MPV, de Sá LRM, Davies YM, Pereira CBP, Martins FH, Munhoz DD, Abe CM, Franzolin MR, Dos Santos LF, Guth BEC, Elias WP, Piazza RMF, Knöbl T. Novel Hybrid of Typical Enteropathogenic Escherichia coli and Shiga-Toxin-Producing E. coli (tEPEC/STEC) Emerging From Pet Birds. Front Microbiol 2018; 9:2975. [PMID: 30574131 PMCID: PMC6291465 DOI: 10.3389/fmicb.2018.02975] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 11/19/2018] [Indexed: 12/01/2022] Open
Abstract
Exotic psittacine birds have been implicated as reservoir of diarrheagenic Escherichia coli (E. coli), including enteropathogenic E. coli (EPEC) and Shiga-toxin producing E. coli (STEC). Here, we present a genotypic and phenotypic characterization of typical EPEC/STEC hybrid strains isolated from exotic psittacine birds. The strains were positive for eae, bfpA, and stx2f genes, belong to serotype O137:H6 and ST2678. Two strains were subject to whole genome sequencing, confirming the presence of the virulence factors of both E. coli pathotypes. Phenotypical in vitro tests confirmed their ability to adhere to HeLa cells and cause cytotoxicity to Vero cells. The rabbit ileal loop assays showed the attaching and effacing lesion, in addition to inflammatory process and overproduction of intestinal mucus. This is the first report of hybrid typical EPEC/STEC (O137:H6/ST2678) strains isolated from companion psittacine birds and the results suggest zoonotic risks.
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Affiliation(s)
- Rosely Martins Gioia-Di Chiacchio
- Department of Pathology, School of Veterinary Medicine and Animal Science, São Paulo, Brazil.,School of Veterinary Medicine, Paulista University, São Paulo, Brazil
| | | | | | - Yamê Minieiro Davies
- Department of Pathology, School of Veterinary Medicine and Animal Science, São Paulo, Brazil
| | | | | | | | | | | | | | | | | | | | - Terezinha Knöbl
- Department of Pathology, School of Veterinary Medicine and Animal Science, São Paulo, Brazil
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19
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Dextran Sulfate Sodium Colitis Facilitates Colonization with Shiga Toxin-Producing Escherichia coli: a Novel Murine Model for the Study of Shiga Toxicosis. Infect Immun 2018; 86:IAI.00530-18. [PMID: 30150257 DOI: 10.1128/iai.00530-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 08/23/2018] [Indexed: 12/23/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) bacteria are globally important gastrointestinal pathogens causing hemorrhagic gastroenteritis with variable progression to potentially fatal Shiga toxicosis. Little is known about the potential effects of E. coli-derived Shiga-like toxins (STXs) on host gastrointestinal immune responses during infection, in part due to the lack of a reproducible immunocompetent-animal model of STEC infection without depleting the commensal microbiota. Here, we describe a novel and reproducible murine model utilizing dextran sulfate sodium (DSS) colitis to induce susceptibility to colonization with clinical-isolate STEC strains. After exposure to DSS and subsequent oral STEC challenge, all the mice were colonized, and 66% of STEC-infected mice required early euthanasia. Morbidity during STEC infection, but not infection with an isogenic STEC mutant with toxin deleted, was associated with increased renal transcripts of the injury markers KIM1 and NGAL, histological evidence of renal tubular injury, and increased renal interleukin 6 gene (IL-6) and CXCL1 inflammatory transcripts. Interestingly, the intestinal burden of STEC during infection was increased compared to its isogenic Shiga toxin deletion strain. Increased bacterial burdens during Shiga toxin production coincided with decreased induction of colonic IL-23 axis transcripts known to be critical for clearance of similar gastrointestinal pathogens in mice, suggesting a previously undescribed role for STEC Shiga toxins in suppressing host immune responses during STEC infection and survival. The DSS+STEC model establishes infection with clinical-isolate strains of STEC in immunocompetent mice without depleting the gastrointestinal microbiota, enabling characterization of the effects of STXs on the IL-23 axis and other gastrointestinal pathogen-host interactions.
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20
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Characterization of a novel plasmid encoding F4-like fimbriae present in a Shiga-toxin producing enterotoxigenic Escherichia coli isolated during the investigation on a case of hemolytic-uremic syndrome. Int J Med Microbiol 2018; 308:947-955. [PMID: 30030028 DOI: 10.1016/j.ijmm.2018.07.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/06/2018] [Accepted: 07/10/2018] [Indexed: 11/21/2022] Open
Abstract
In February 2017 a case of Hemolytic-Uremic Syndrome (HUS) was reported to the National Registry of HUS in an adult living in Northern Italy. Stool specimens from the patient and his family contacts were collected and the analyses led to the isolation of a Locus of Enterocyte Effacement (LEE)-negative Shiga toxin 2 (Stx2)-producing Escherichia coli. The epidemiological investigations performed brought to collect fecal samples from the animals reared in a farm held by the case's family and a mixture of bovine and swine feces proved positive for Shiga toxin-producing E. coli (STEC) and yielded the isolation of a LEE-negative stx2-positive E. coli strain. Further characterization by whole genome sequencing led to identify the isolates as two identical O2:H27 hybrid Enterotoxigenic Shiga toxin-producing E. coli (ETEC-STEC). Sequencing of a high molecular weight plasmid present in the human isolate disclosed a peculiar plasmid harboring virulence genes characteristic for both pathotypes, including the enterohemolysin-coding gene and sta1, encoding the heat stable enterotoxin. Moreover, a complete fae locus encoding the ETEC F4 fimbriae could be identified, including a novel variant of faeG gene responsible for the production of the main structural subunit of the fimbriae. This novel faeG showed great diversity in the nucleotidic sequence when compared with the reference genes encoding the swine F4 allelic variants, whereas at the amino acid sequence level the predicted protein sequence showed some similarity with FaeG from E. coli strains of bovine origin. Further investigation on the plasmid region harboring the newly identified faeG allelic variant allowed to identify similar plasmids in NCBI sequence database, as part of the genome of other previously uncharacterized ETEC-STEC strains of bovine origin, suggesting that the novel F4-like fimbriae may play a role in bovine host specificity.
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Species-Wide Collection of Escherichia coli Isolates for Examination of Genomic Diversity. GENOME ANNOUNCEMENTS 2017; 5:5/50/e01321-17. [PMID: 29242221 PMCID: PMC5730671 DOI: 10.1128/genomea.01321-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pathogenic and nonpathogenic Escherichia coli strains present a vast genomic diversity. We report the genome sequences of 2,244 E. coli isolates from multiple animal and environmental sources. Their phylogenetic relationships and potential risk to human health were examined.
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Induction of Shiga Toxin-Encoding Prophage by Abiotic Environmental Stress in Food. Appl Environ Microbiol 2017; 83:AEM.01378-17. [PMID: 28778890 DOI: 10.1128/aem.01378-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 07/24/2017] [Indexed: 11/20/2022] Open
Abstract
The prophage-encoded Shiga toxin is a major virulence factor in Stx-producing Escherichia coli (STEC). Toxin production and phage production are linked and occur after induction of the RecA-dependent SOS response. However, food-related stress and Stx-prophage induction have not been studied at the single-cell level. This study investigated the effects of abiotic environmental stress on stx expression by single-cell quantification of gene expression in STEC O104:H4 Δstx2::gfp::ampr In addition, the effect of stress on production of phage particles was determined. The lethality of stressors, including heat, HCl, lactic acid, hydrogen peroxide, and high hydrostatic pressure, was selected to reduce cell counts by 1 to 2 log CFU/ml. The integrity of the bacterial membrane after exposure to stress was measured by propidium iodide (PI). The fluorescent signals of green fluorescent protein (GFP) and PI were quantified by flow cytometry. The mechanism of prophage induction by stress was evaluated by relative gene expression of recA and cell morphology. Acid (pH < 3.5) and H2O2 (2.5 mM) induced the expression of stx2 in about 18% and 3% of the population, respectively. The mechanism of prophage induction by acid differs from that of induction by H2O2 H2O2 induction but not acid induction corresponded to production of infectious phage particles, upregulation of recA, and cell filamentation. Pressure (200 MPa) or heat did not induce the Stx2-encoding prophage (Stx2-prophage). Overall, the quantification method developed in this study allowed investigation of prophage induction and physiological properties at the single-cell level. H2O2 and acids mediate different pathways to induce Stx2-prophage.IMPORTANCE Induction of the Stx-prophage in STEC results in production of phage particles and Stx and thus relates to virulence as well as the transduction of virulence genes. This study developed a method for a detection of the induction of Stx-prophages at the single-cell level; membrane permeability and an indication of SOS response to environmental stress were additionally assessed. H2O2 and mitomycin C induced expression of the prophage and activated a SOS response. In contrast, HCl and lactic acid induced the Stx-prophage but not the SOS response. The lifestyle of STEC exposes the organism to intestinal and extraintestinal environments that impose oxidative and acid stress. A more thorough understanding of the influence of food processing-related stressors on Stx-prophage expression thus facilitates control of STEC in food systems by minimizing prophage induction during food production and storage.
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Wang W, Zijlstra RT, Gänzle MG. Identification and quantification of virulence factors of enterotoxigenic Escherichia coli by high-resolution melting curve quantitative PCR. BMC Microbiol 2017; 17:114. [PMID: 28506262 PMCID: PMC5433089 DOI: 10.1186/s12866-017-1023-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 05/05/2017] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Diagnosis of enterotoxigenic E. coli (ETEC) associated diarrhea is complicated by the diversity of E.coli virulence factors. This study developed a multiplex quantitative PCR assay based on high-resolution melting curves analysis (HRM-qPCR) to identify and quantify genes encoding five ETEC fimbriae related to diarrhea in swine, i.e. K99, F41, F18, F6 and K88. METHODS Five fimbriae expressed by ETEC were amplified in multiple HRM-qPCR reactions to allow simultaneous identification and quantification of five target genes. The assay was calibrated to allow quantification of the most abundant target gene, and validated by analysis of 30 samples obtained from piglets with diarrhea and healthy controls, and comparison to standard qPCR detection. RESULTS The five amplicons with melting temperatures (Tm) ranging from 74.7 ± 0.06 to 80.5 ± 0.15 °C were well-separated by HRM-qPCR. The area of amplicons under the melting peak correlated linearly to the proportion of the template in the calibration mixture if the proportion exceeded 4.8% (K88) or <1% (all other amplicons). The suitability of the method was evaluated using 30 samples from weaned pigs aged 6-7 weeks; 14 of these animals suffered from diarrhea in consequence of poor sanitary conditions. Genes encoding fimbriae and enterotoxins were quantified by HRM-qPCR and/or qPCR. The multiplex HRM-qPCR allowed accurate analysis when the total gene copy number of targets was more than 1 × 105 / g wet feces and the HRM curves were able to simultaneously distinguish fimbriae genes in the fecal samples. The relative quantification of the most abundant F18 based on melting peak area was highly correlated (P < 0.001; r2 = 0.956) with that of individual qPCR result but the correlation for less abundant fimbriae was much lower. CONCLUSIONS The multiplex HRM assay identifies ETEC virulence factors specifically and efficiently. It correctly indicated the predominant fimbriae type and additionally provides information of presence/ absence of other fimbriae types and it could find broad applications for pathogen diagnosis.
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Affiliation(s)
- Weilan Wang
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For Centre, Edmonton, AB, T6G 2P5, Canada
| | - Ruurd T Zijlstra
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For Centre, Edmonton, AB, T6G 2P5, Canada
| | - Michael G Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For Centre, Edmonton, AB, T6G 2P5, Canada.
- College of Bioengineering and Food Science, Hubei University of Technology, Wuhan, Hubei, People's Republic of China.
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Johura FT, Parveen R, Islam A, Sadique A, Rahim MN, Monira S, Khan AR, Ahsan S, Ohnishi M, Watanabe H, Chakraborty S, George CM, Cravioto A, Navarro A, Hasan B, Alam M. Occurrence of Hybrid Escherichia coli Strains Carrying Shiga Toxin and Heat-Stable Toxin in Livestock of Bangladesh. Front Public Health 2017; 4:287. [PMID: 28119905 PMCID: PMC5221120 DOI: 10.3389/fpubh.2016.00287] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 12/19/2016] [Indexed: 11/13/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) and enterotoxigenic E. coli (ETEC) are important causes of diarrhea in humans and animals worldwide. Although ruminant animals are the main source of STEC, diarrhea due to this pathotype is very low in Bangladesh where ETEC remains the predominant group associated with childhood diarrhea. In the present study, E. coli strains (n = 35) isolated from Bangladesh livestock (goats, sheep, and cattle) and poultry (chicken and ducks) were analyzed for the presence of major virulence factors, such as Shiga toxins (STX-1 and STX-2), heat-labile toxin, and heat-stable toxins (STa and STb). Multiplex polymerase chain reaction results revealed 23 (66%) E. coli strains to be virulent possessing either sta (n = 5), stx (stx1, n = 8; stx2, n = 2), or both (n = 8) genes in varying combinations. Thirty-four percent (8/23) of strains from livestock were hybrid type that carried both stx (either stx1 or stx2) and ETEC-specific enterotoxin gene sta. Serotyping results revealed that the ETEC strains belonged to five serotypes, namely O36:H5, O174:H-, O152:H8, O109:H51, and O8:H21, while the STEC-producing strains belonged to serotypes O76:H19 (n = 3), O43:H2 (n = 2), O87:H16 (n = 2), OR:H2 (n = 1), O110:H16 (n = 1), and O152:H8 (n = 1). The STEC-ETEC hybrid strains belonged to serotypes O76:H19 (n = 3), O43:H2 (n = 2), O87:H16, OR:H2, and O152:H8. Forty percent (2/5) of the ETEC and 20% (2/10) of the STEC strains were multidrug resistant with the highest drug resistance (50%) being found in the hybrid strains. Molecular fingerprinting determined by pulsed-field gel electrophoresis and cluster analyses by dendrogram revealed that, genetically, STEC-ETEC hybrid strains were highly heterogeneous. Multidrug-resistant E. coli STEC-ETEC hybrid strains in domesticated animals pose a public health threat for humans in Bangladesh.
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Affiliation(s)
- Fatema-Tuz Johura
- International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Rozina Parveen
- International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Atiqul Islam
- International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Abdus Sadique
- International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Md Niaz Rahim
- International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Shirajum Monira
- International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Anisur R. Khan
- Department of Microbiology, University of Dhaka, Dhaka, Bangladesh
| | - Sunjukta Ahsan
- Department of Microbiology, University of Dhaka, Dhaka, Bangladesh
| | | | | | | | | | - Alejandro Cravioto
- International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Armando Navarro
- Department of Public Health, Faculty of Medicine, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Badrul Hasan
- Infectious Disease, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Munirul Alam
- International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
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Leonard SR, Mammel MK, Lacher DW, Elkins CA. Strain-Level Discrimination of Shiga Toxin-Producing Escherichia coli in Spinach Using Metagenomic Sequencing. PLoS One 2016; 11:e0167870. [PMID: 27930729 PMCID: PMC5145215 DOI: 10.1371/journal.pone.0167870] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 11/21/2016] [Indexed: 11/28/2022] Open
Abstract
Consumption of fresh bagged spinach contaminated with Shiga toxin-producing Escherichia coli (STEC) has led to severe illness and death; however current culture-based methods to detect foodborne STEC are time consuming. Since not all STEC strains are considered pathogenic to humans, it is crucial to incorporate virulence characterization of STEC in the detection method. In this study, we assess the comprehensiveness of utilizing a shotgun metagenomics approach for detection and strain-level identification by spiking spinach with a variety of genomically disparate STEC strains at a low contamination level of 0.1 CFU/g. Molecular serotyping, virulence gene characterization, microbial community analysis, and E. coli core gene single nucleotide polymorphism (SNP) analysis were performed on metagenomic sequence data from enriched samples. It was determined from bacterial community analysis that E. coli, which was classified at the phylogroup level, was a major component of the population in most samples. However, in over half the samples, molecular serotyping revealed the presence of indigenous E. coli which also contributed to the percent abundance of E. coli. Despite the presence of additional E. coli strains, the serotype and virulence genes of the spiked STEC, including correct Shiga toxin subtype, were detected in 94% of the samples with a total number of reads per sample averaging 2.4 million. Variation in STEC abundance and/or detection was observed in replicate spiked samples, indicating an effect from the indigenous microbiota during enrichment. SNP analysis of the metagenomic data correctly placed the spiked STEC in a phylogeny of related strains in cases where the indigenous E. coli did not predominate in the enriched sample. Also, for these samples, our analysis demonstrates that strain-level phylogenetic resolution is possible using shotgun metagenomic data for determining the genomic relatedness of a contaminating STEC strain to other closely related E. coli.
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Affiliation(s)
- Susan R. Leonard
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland, United States of America
| | - Mark K. Mammel
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland, United States of America
| | - David W. Lacher
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland, United States of America
| | - Christopher A. Elkins
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland, United States of America
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