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Kiss C, Kotsanas D, Francis MJ, Sait M, Valcanis M, Lacey J, Connelly K, Rogers B, Ballard SA, Howden BP, Graham M. Molecular epidemiology, clinical features and significance of Shiga toxin detection from routine testing of gastroenteritis specimens. Pathology 2023:S0031-3025(23)00119-8. [PMID: 37271611 DOI: 10.1016/j.pathol.2023.03.005] [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: 10/10/2022] [Revised: 02/20/2023] [Accepted: 03/07/2023] [Indexed: 06/06/2023]
Abstract
After introduction of faecal multiplex PCR that includes targets for stx1 and stx2 genes, we found stx genes were detected in 120 specimens from 111 patients over a 31-month period from 2018-2020 from a total of 14,179 separate tests performed. The proportion of stx1 only vs stx2 only vs stx1 and stx2 was 35%, 22% and 42%, respectively. There were 54 specimens which were culture positive, with 33 different serotypes identified, the predominant serotype being O157:H7 (19%). Eighty-two patients had clinical data available; we found a high rate of fever (35%), bloody diarrhoea (34%), acute kidney injury (27%), hospital admission (80%) and detection of faecal co-pathogens (23%). Only one patient developed haemolytic uraemic syndrome. We found no significant association with stx genotype and any particular symptom or complication. We found a significant association of serotypes O157:H7 and O26:H11 with bloody stool, but no significant association with any other symptom or complication.
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Affiliation(s)
- Christopher Kiss
- Department of Microbiology, Monash Health, Clayton, Vic, Australia.
| | - Despina Kotsanas
- Monash Infectious Diseases, Monash Health, Clayton, Vic, Australia
| | | | - Michelle Sait
- Microbiological Diagnostic Unit Public Health Laboratory, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Vic, Australia
| | - Mary Valcanis
- Microbiological Diagnostic Unit Public Health Laboratory, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Vic, Australia
| | - Jake Lacey
- Microbiological Diagnostic Unit Public Health Laboratory, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Vic, Australia
| | - Kathryn Connelly
- Faculty of Medicine Nursing and Health Sciences, Monash University, Clayton, Vic, Australia; Monash University School of Clinical Sciences, Monash Health, Clayton, Vic, Australia
| | - Benjamin Rogers
- Monash Infectious Diseases, Monash Health, Clayton, Vic, Australia; Faculty of Medicine Nursing and Health Sciences, Monash University, Clayton, Vic, Australia
| | - Susan A Ballard
- Microbiological Diagnostic Unit Public Health Laboratory, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Vic, Australia
| | - Benjamin P Howden
- Microbiological Diagnostic Unit Public Health Laboratory, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Vic, Australia; Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Vic, Australia
| | - Maryza Graham
- Department of Microbiology, Monash Health, Clayton, Vic, Australia; Monash Infectious Diseases, Monash Health, Clayton, Vic, Australia; Microbiological Diagnostic Unit Public Health Laboratory, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Vic, Australia; Faculty of Medicine Nursing and Health Sciences, Monash University, Clayton, Vic, Australia
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Characterisation of atypical Shiga toxin gene sequences and description of Stx2j, a new subtype. J Clin Microbiol 2022; 60:e0222921. [PMID: 35225693 DOI: 10.1128/jcm.02229-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shiga toxin (Stx) is the definitive virulence factor of Shiga toxin-producing Escherichia coli (STEC). Stx variants are currently organised into a taxonomic system of three Stx1 (a,c,d) and seven Stx2 (a,b,c,d,e,f,g) subtypes. In this study, seven STEC isolates from food and clinical samples possessing stx2 sequences that do not fit current Shiga toxin taxonomy were identified. Genome assemblies of the STEC strains was created from Oxford Nanopore and Illumina sequence data. The presence of atypical stx2 sequences were confirmed by Sanger sequencing, as were Stx2 expression and cytotoxicity. A strain of O157:H7 was found to possess stx1a and a truncated stx2a, which were originally misidentified as an atypical stx2. Two strains possessed unreported variants of Stx2a (O8:H28) and Stx2b (O146:H21). In four of the strains we found three Stx-subtypes that are not included in the current taxonomy. Stx2h (O170:H18) was identified in a Canadian sprout isolate; this subtype has only previously been reported in STEC from Tibetan Marmots. Stx2o (O85:H1) was identified in a clinical isolate. Finally, Stx2j (O158:H23 and O33:H14) was found in lettuce and clinical isolates. The results of this study expands the number of known Stx subtypes, the range of STEC serotypes, and isolation sources in which they may be found. The presence of the Stx2j and Stx2o in clinical isolates of STEC indicates that strains carrying these variants are potential human pathogens. Highlights Atypical Shiga toxin (stx) genes in Escherichia coli were sequenced. Two new variants of stx2a and stx2b are described. Two strains carried subtypes Stx2h and Stx2o, which have only one previous report. Two strains carried a previously undescribed subtype, Stx2j.
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Monitoring the incidence and causes of diseases potentially transmitted by food in Australia: Annual report of the OzFoodNet network, 2013-2015. ACTA ACUST UNITED AC 2021; 45. [PMID: 34139966 DOI: 10.33321/cdi.2021.45.21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Abstract This report summarises the incidence of diseases potentially transmitted by food in Australia, and details outbreaks associated with food that occurred during 2013-2015. OzFoodNet sites reported an increasing number of notifications of 12 diseases or conditions vthat may be transmitted by food (botulism; campylobacteriosis; cholera; hepatitis A; hepatitis E; haemolytic uraemic syndrome (HUS); listeriosis; Salmonella Paratyphi (paratyphoid fever) infection; salmonellosis; shigellosis; Shiga toxin-producing Escherichia coli (STEC) infection; and Salmonella Typhi (typhoid fever) infection), with a total of 28,676 notifications received in 2013; 37,958 in 2014; and 41,226 in 2015. The most commonly-notified conditions were campylobacteriosis (a mean of 19,061 notifications per year over 2013-2015) and salmonellosis (a mean of 15,336 notifications per year over 2013-2015). Over these three years, OzFoodNet sites also reported 512 outbreaks of gastrointestinal illness caused by foodborne, animal-to-person or waterborne disease, affecting 7,877 people, and resulting in 735 hospitalisations and 18 associated deaths. The majority of outbreaks (452/512; 88%) were due to foodborne or suspected foodborne transmission. The remaining 12% of outbreaks were due to waterborne or suspected waterborne transmission (57 outbreaks) and animal-to-human transmission (three outbreaks). Foodborne and suspected foodborne outbreaks affected 7,361 people, resulting in 705 hospitalisations and 18 deaths. Salmonella was the most common aetiological agent identified in foodborne outbreaks (239/452; 53%), and restaurants were the most frequently-reported food preparation setting (211/452; 47%). There were 213 foodborne outbreaks (47%) attributed to a single food commodity during 2013-2015, with 58% (124/213) associated with the consumption of eggs and egg-based dishes.
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Affiliation(s)
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- Australian Government Department of Health
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Pintara A, Jennison A, Rathnayake IU, Mellor G, Huygens F. Core and Accessory Genome Comparison of Australian and International Strains of O157 Shiga Toxin-Producing Escherichia coli. Front Microbiol 2020; 11:566415. [PMID: 33013798 PMCID: PMC7498637 DOI: 10.3389/fmicb.2020.566415] [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: 05/27/2020] [Accepted: 08/17/2020] [Indexed: 12/20/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen, and serotype O157:H7 is typically associated with severe disease. Australian STEC epidemiology differs from many other countries, as severe outbreaks and HUS cases appear to be more often associated with non-O157 serogroups. It is not known why Australian strains of O157 STEC might differ in virulence to international strains. Here we investigate the reduced virulence of Australian strains. Multiple genetic analyses were performed, including SNP-typing, to compare the core genomes of the Australian to the international isolates, and accessory genome analysis to determine any significant differences in gene presence/absence that could be associated with their phenotypic differences in virulence. The most distinct difference between the isolates was the absence of the stx2a gene in all Australian isolates, with few other notable differences observed in the core and accessory genomes of the O157 STEC isolates analyzed in this study. The presence of stx1a in most Australian isolates was another notable observation. Acquisition of stx2a seems to coincide with the emergence of highly pathogenic STEC. Due to the lack of other notable genotypic differences observed between Australian and international isolates characterized as highly pathogenic, this may be further evidence that the absence of stx2a in Australian O157 STEC could be a significant characteristic defining its mild virulence. Further work investigating the driving force(s) behind Stx prophage loss and acquisition is needed to determine if this potential exists in Australian O157 isolates.
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Affiliation(s)
- Alexander Pintara
- Centre for Immunology and Infection Control, Queensland University of Technology, Herston, QLD, Australia
- School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia
| | - Amy Jennison
- Public Health Microbiology, Forensic and Scientific Services, Queensland Health, Brisbane, QLD, Australia
| | - Irani U. Rathnayake
- Public Health Microbiology, Forensic and Scientific Services, Queensland Health, Brisbane, QLD, Australia
| | - Glen Mellor
- CSIRO Animal, Food and Health Sciences, Archerfield, QLD, Australia
| | - Flavia Huygens
- Centre for Immunology and Infection Control, Queensland University of Technology, Herston, QLD, Australia
- School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia
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5
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Bolukaoto JY, Kock MM, Strydom KA, Mbelle NM, Ehlers MM. Molecular characteristics and genotypic diversity of enterohaemorrhagic Escherichia coli O157:H7 isolates in Gauteng region, South Africa. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 692:297-304. [PMID: 31351277 DOI: 10.1016/j.scitotenv.2019.07.119] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 07/04/2019] [Accepted: 07/08/2019] [Indexed: 06/10/2023]
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 is one of the major foodborne and waterborne pathogens causing severe diseases and outbreaks worldwide. There is scarcity of EHEC O157:H7 data in South Africa. This study was carried out to determine the molecular characteristics and genotypic diversity of EHEC O157:H7 isolates in the Gauteng region, South Africa. Samples were cultured on selective chromogenic media. Antibiotic susceptibility profile of isolates was determined using the VITEK®-2 automated system. Isolates were characterised using multiplex PCR assays and the genetic diversity was determined using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). A total of 520 samples of which 270 environmental water samples and 250 stool specimens were collected and analysed. Overall, EHEC O157:H7 was recovered from 2.3% (12/520) of samples collected. Environmental water samples and clinical stool specimens showed a prevalence of 4.07% (11/270) and 0.4% (1/250) respectively. Antibiotic susceptibility profile varied from isolates with full susceptibility to isolates with resistance to multiple antibiotics. Most resistance was detected to the penicillins, specifically ampicillin (7/12), amoxicillin (3/12) and piperacillin/Tazobactam (3/12) followed by one of the folate inhibitors, trimethoprim (3/12) and the carbapenems, imipenem and meropenem (2/12) each. Three isolates harboured a combination of Shiga-toxins (Stx)-2, intimin (eae) and enterohaemolysin (hlyA) genes, while two isolates harboured the Stx-1, Stx-2 and hlyA genes. The PFGE performed showed that EHEC O157:H7 isolates were genetically diverse, with two minor pulsotypes and eight singletons. The MLST analysis identified three sequence types (STs) (ST10, ST11 and ST1204) that have been previously reported associated with outbreaks. The STs identified in this study pose a potential public health risk to consumers of untreated environmental water and closed human contacts. There is necessity to enhance surveillance in reducing the propagation of this bacterium which is a public health problem.
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Affiliation(s)
- John Y Bolukaoto
- Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, South Africa
| | - Marleen M Kock
- Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, South Africa; National Health Laboratory Service, Tshwane Academic Division, Pretoria, South Africa
| | - Kathy-Anne Strydom
- Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, South Africa; Ampath National Laboratory Service, Pretoria, South Africa
| | - Nontombi M Mbelle
- Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, South Africa; National Health Laboratory Service, Tshwane Academic Division, Pretoria, South Africa
| | - Marthie M Ehlers
- Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, South Africa; National Health Laboratory Service, Tshwane Academic Division, Pretoria, South Africa.
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Ingle DJ, Gonçalves da Silva A, Valcanis M, Ballard SA, Seemann T, Jennison AV, Bastian I, Wise R, Kirk MD, Howden BP, Williamson DA. Emergence and divergence of major lineages of Shiga-toxin-producing Escherichia coli in Australia. Microb Genom 2019; 5. [PMID: 31107203 PMCID: PMC6562248 DOI: 10.1099/mgen.0.000268] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Shiga-toxin-producing Escherichia coli (STEC) infection is an important global cause of foodborne disease. To date however, genomics-based studies of STEC have been predominately focused upon STEC collected in the Northern Hemisphere. Here, we demonstrate the population structure of 485 STEC isolates in Australia, and show that several clonal groups (CGs) common to Australia were infrequently detected in a representative selection of contemporary STEC genomes from around the globe. Further, phylogenetic analysis demonstrated that lineage II of the global O157:H7 STEC was most prevalent in Australia, and was characterized by a frameshift mutation in flgF, resulting in the H-non-motile phenotype. Strong concordance between in silico and phenotypic serotyping was observed, along with concordance between in silico and conventional detection of stx genes. These data represent the most comprehensive STEC analysis from the Southern Hemisphere, and provide a framework for future national genomics-based surveillance of STEC in Australia.
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Affiliation(s)
- Danielle J. Ingle
- Microbiological Diagnostic Unit Public Health Laboratory at the University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
- National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australia
| | - Anders Gonçalves da Silva
- Microbiological Diagnostic Unit Public Health Laboratory at the University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Mary Valcanis
- Microbiological Diagnostic Unit Public Health Laboratory at the University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Susan A. Ballard
- Microbiological Diagnostic Unit Public Health Laboratory at the University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Torsten Seemann
- Microbiological Diagnostic Unit Public Health Laboratory at the University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
- Melbourne Bioinformatics Group, Victoria, Australia
| | - Amy V. Jennison
- Public Health Microbiology, Forensic and Scientific Services, Queensland Department of Health, Queensland, Australia
| | | | - Rolf Wise
- SA Pathology, South Australia, Australia
| | - Martyn D. Kirk
- National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australia
| | - Benjamin P. Howden
- Microbiological Diagnostic Unit Public Health Laboratory at the University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
- Doherty Applied Microbial Genomics, Department Microbiology and Immunology, The University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Deborah A. Williamson
- Microbiological Diagnostic Unit Public Health Laboratory at the University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
- *Correspondence: Deborah A. Williamson,
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7
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Williamson DA, Kirk MD, Sintchenko V, Howden BP. The importance of public health genomics for ensuring health security for Australia. Med J Aust 2019; 210:295-297.e1. [PMID: 30888069 DOI: 10.5694/mja2.50063] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
| | - Martyn D Kirk
- National Centre for Epidemiology and Population Health, Australian National University, Canberra, ACT
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8
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Silva CJ, Lee BG, Yambao JC, Erickson-Beltran ML, Quiñones B. Using Nanospray Liquid Chromatography and Mass Spectrometry to Quantitate Shiga Toxin Production in Environmental Escherichia coli Recovered from a Major Produce Production Region in California. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:1554-1562. [PMID: 30485086 DOI: 10.1021/acs.jafc.8b05324] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A set of 45 environmental strains of Shiga toxin producing Escherichia coli (STEC) from three California counties were analyzed for Shiga toxin production by nanospray liquid chromatography-mass spectrometry and Vero cell bioassay. The STEC in this set comprised six serotypes ((O113:H21, O121:H19, O157:H7, O6:H34, O177:H25, and O185:H7) each containing either the stx2a or stx2c operon. Six of the seven O113:H21 were found to contain two distinct stx2a operons. Eight strains of O157:H7 possessed a stx2c operon whose A subunit gene was interrupted by an insertion sequence (IS1203v). Shiga toxin production was induced by nutrient depletion and quantitated by mass spectrometry. The 37 strains produced Shiga toxins in a near 50-fold range (1.4-49 ng/mL). The IS-interrupted strains expressed low but measurable amounts of the B subunits (0.5-1.9 ng/mL). Another strain possessed an identical stx operon without an IS interruption and produced intact Stx2c (5.7 ng/mL).
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Affiliation(s)
- Christopher J Silva
- Produce Safety & Microbiology Research Unit , U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center , Albany , California 94710 , United States
| | - Bertram G Lee
- Produce Safety & Microbiology Research Unit , U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center , Albany , California 94710 , United States
| | - Jaszemyn C Yambao
- Produce Safety & Microbiology Research Unit , U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center , Albany , California 94710 , United States
| | - Melissa L Erickson-Beltran
- Produce Safety & Microbiology Research Unit , U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center , Albany , California 94710 , United States
| | - Beatriz Quiñones
- Produce Safety & Microbiology Research Unit , U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center , Albany , California 94710 , United States
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Raeisi M, Ghorbani Bidkorpeh F, Hashemi M, Tepe B, Moghaddam Z, Aman Mohammadi M, Noori SMA. Chemical Composition and Antibacterial and Antioxidant Properties of Essential Oils of Zataria multiflora, Artemisia deracunculus and Mentha piperita. MEDICAL LABORATORY JOURNAL 2019. [DOI: 10.29252/mlj.13.2.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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10
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Bai X, Mernelius S, Jernberg C, Einemo IM, Monecke S, Ehricht R, Löfgren S, Matussek A. Shiga Toxin-Producing Escherichia coli Infection in Jönköping County, Sweden: Occurrence and Molecular Characteristics in Correlation With Clinical Symptoms and Duration of stx Shedding. Front Cell Infect Microbiol 2018; 8:125. [PMID: 29765909 PMCID: PMC5939558 DOI: 10.3389/fcimb.2018.00125] [Citation(s) in RCA: 18] [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: 02/12/2018] [Accepted: 04/13/2018] [Indexed: 11/13/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) cause bloody diarrhea (BD), hemorrhagic colitis (HC), and even hemolytic uremic syndrome (HUS). In Nordic countries, STEC are widely spread and usually associated with gastrointestinal symptoms and HUS. The objective of this study was to investigate the occurrence of STEC in Swedish patients over 10 years of age from 2003 through 2015, and to analyze the correlation of critical STEC virulence factors with clinical symptoms and duration of stx shedding. Diarrheal stool samples were screened for presence of stx by real-time PCR. All STEC isolates were characterized by DNA microarray assay and PCR to determine serogenotypes, stx subtypes, and presence of intimin gene eae and enterohaemolysin gene ehxA. Multilocus sequencing typing (MLST) was used to assess phylogenetic relationships. Clinical features were collected and analyzed using data from the routine infection control measures in the county. A total of 14,550 samples were enrolled in this 12-years period study, and 175 (1.2%) stools were stx positive by real-time PCR. The overall incidence of STEC infection was 4.9 cases per 100,000 person-years during the project period. Seventy-five isolates, with one isolate per sample were recovered, among which 43 were from non-bloody stools, 32 from BD, and 3 out of the 75 STEC positive patients developed HUS. The presence of stx2 in both stools and isolates were associated with BD (p = 0.008, p = 0.05), and the presence of eae in isolates was related to BD (p = 0.008). The predominant serogenotypes associated with BD were O157:H7, O26:H11, O121:H19, and O103:H2. Isolates from HUS were O104:H4 and O98: H21 serotypes. Phylogenetic analysis revealed our strains were highly diverse, and showed close relatedness to HUS-associated STEC collection strains. In conclusion, the presence of stx2 in stool was related to BD already at the initial diagnostic procedure, thus could be used as risk predictor at an early stage. STEC isolates with stx2 and eae were significantly associated with BD. The predominant serotypes associated with BD were O157:H7, O26:H11, O121:H19, and O103:H2. Nevertheless, the pathogenic potential of other serotypes and genotypes should not be neglected.
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Affiliation(s)
- Xiangning Bai
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Karolinska University Hospital, Huddinge, Sweden
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | | | | | | | - Stefan Monecke
- Abbott (Alere Technologies GmbH), Jena, Germany
- Institute for Medical Microbiology and Hygiene, Technische Universität Dresden, Dresden, Germany
- InfectoGnostics Research Campus, Jena, Germany
| | - Ralf Ehricht
- Institute for Medical Microbiology and Hygiene, Technische Universität Dresden, Dresden, Germany
- InfectoGnostics Research Campus, Jena, Germany
| | - Sture Löfgren
- Department of Laboratory Medicine, Jönköping, Sweden
| | - Andreas Matussek
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Karolinska University Hospital, Huddinge, Sweden
- Department of Laboratory Medicine, Jönköping, Sweden
- Karolinska University Laboratory, Stockholm, Sweden
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11
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Molecular Prediction of the O157:H-Negative Phenotype Prevalent in Australian Shiga Toxin-Producing Escherichia coli Cases Improves Concordance of In Silico Serotyping with Phenotypic Motility. J Clin Microbiol 2018; 56:JCM.01906-17. [PMID: 29367299 DOI: 10.1128/jcm.01906-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 01/17/2018] [Indexed: 11/20/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen, and serotype O157:H7 is typically associated with severe disease. Australia is unique in its STEC epidemiology, as severe cases are typically associated with non-O157 serogroups, and locally acquired O157 isolates are H-negative/nonmotile. The H-negative phenotype and reduced severity of disease compared to that associated with H7/motile strains are distinct features of Australian O157 strains, but the molecular mechanism behind this phenotype has not been reported. Accurate characterization of the H-negative phenotype is important in epidemiological surveillance of STEC. Serotyping is moving away from phenotype-based methods, as next generation sequencing allows rapid extrapolation of serotype through in silico detection of the O-antigen processing genes, wzx, wzy, wzm, and wzt, and the H-antigen gene, fliC The detection and genotyping of fliC alone is unable to determine the motility of the strain. Typically, most Australian O157:H-negative strains carry an H7 genotype yet phenotypically are nonmotile; thus, many are mischaracterized as H7 strains by in silico serotyping tools. Comparative genomic analysis of flagellar genes between Australian and international isolates was performed and an insertion at nucleotide (nt) 125 in the flgF gene was identified in H-negative isolates. Chi-square results showed that this insertion was significantly associated with the H-negative phenotype (P < 0.0001). Phylogenetic analysis was also completed and showed that the Australian H-negative isolates with the insertion in flgF represent a clade within the O157 serogroup, distinct from O157:H7 serotypes. This study provides a genetic target for inferring the nonmotile phenotype of Australian O157 STEC, which increases the predictive value of in silico serotyping.
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