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McMahon T, Clarke S, Deschênes M, Tapp K, Blais B, Gill A. Real-time PCR primers and probes for the detection of Shiga toxin genes, including novel subtypes. Int J Food Microbiol 2024; 419:110744. [PMID: 38763050 DOI: 10.1016/j.ijfoodmicro.2024.110744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 05/03/2024] [Accepted: 05/10/2024] [Indexed: 05/21/2024]
Abstract
Shiga toxin-producing Escherichia coli (STEC) are foodborne enteric pathogens. STEC are differentiated from other E. coli by detection of Shiga toxin (Stx) or its gene (stx). The established nomenclature of Stx identifies ten subtypes (Stx1a, Stx1c, Stxd, Stx2a to Stx2g). An additional nine subtypes have been reported and described (Stx1e, Stx2h to Stx2o). Many PCR protocols only detect a subset of Stx subtypes which limits their inclusivity. Here we describe a real-time PCR assay inclusive of the DNA sequences of representatives of all currently described Stx subtypes. A multiplex real-time PCR assay for detection of stx was developed using nine primers and four probes. Since the identification of STEC does not require differentiation of stx subtypes, the probes use the same fluorescent reporter to enable detection of multiple possible targets in a single reaction. The PCR mixture includes an internal positive control to detect inhibition of the reaction. Thus, the protocol can be performed on a two-channel real-time PCR platform. To reduce the biosafety risk inherent in the use of STEC cultures as process controls, the protocol also includes the option of a non-pathogenic E. coli transformant carrying a plasmid encoding the targeted fragment of the stx2a sequence. The inclusivity of the PCR was assessed against colonies of 137 STEC strains and one strain of Shigella dysenteriae, including strains carrying single copies of stx representing fourteen subtypes (stx1 a, c, d; stx2 a-j and o). Five additional subtypes (stx1e, 2k, 2l, 2m and 2n) were represented by E. coli transformed with plasmids encoding toxoid (enzymatically inactive A subunit) sequences. The exclusivity panel consisted of 70 bacteria, including 21 stx-negative E. coli. Suitability for food analysis was assessed with artificially inoculated ground beef, spinach, cheese, and apple cider. The real-time PCR generated positive results for all 19 stx subtypes, represented by colonies of STEC, S. dysenteriae and E. coli transformants carrying stx toxoid plasmids. Tests of exclusivity panel colonies were all negative. The real-time PCR detected the presence of stx in all inoculated food enrichments tested, and the presence of STEC was confirmed by isolation.
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Affiliation(s)
- Tanis McMahon
- Health Canada/Santé Canada, Bureau of Microbial Hazards, Ottawa, Ontario, Canada
| | - Sarah Clarke
- Health Canada/Santé Canada, Bureau of Microbial Hazards, Ottawa, Ontario, Canada
| | - Mylène Deschênes
- Canadian Food Inspection Agency/Agence canadienne d'inspection des aliments, Ottawa Laboratory Carling, Ottawa, Ontario, Canada
| | - Kyle Tapp
- Canadian Food Inspection Agency/Agence canadienne d'inspection des aliments, Ottawa Laboratory Carling, Ottawa, Ontario, Canada
| | - Burton Blais
- Canadian Food Inspection Agency/Agence canadienne d'inspection des aliments, Ottawa Laboratory Carling, Ottawa, Ontario, Canada
| | - Alexander Gill
- Health Canada/Santé Canada, Bureau of Microbial Hazards, Ottawa, Ontario, Canada.
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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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Tarr GAM, Lin CY, Vandermeer B, Lorenzetti DL, Tarr PI, Chui L, Hartling L, Freedman SB. Diagnostic Test Accuracy of Commercial Tests for Detection of Shiga Toxin-Producing Escherichia coli: A Systematic Review and Meta-Analysis. Clin Chem 2020; 66:302-315. [PMID: 32040589 DOI: 10.1093/clinchem/hvz006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 08/07/2019] [Indexed: 12/25/2022]
Abstract
BACKGROUND Rapid detection of Shiga toxin-producing Escherichia coli (STEC) enables appropriate monitoring and treatment. We synthesized available evidence to compare the performance of enzyme immunoassay (EIA) and PCR tests for the detection of STEC. METHODS We searched published and gray literature for studies of STEC EIA and/or PCR diagnostic test accuracy relative to reference standards including at least one nucleic acid amplification test. Two reviewers independently screened studies, extracted data, and assessed quality with the second version of the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Bivariate random effects models were used to meta-analyze the clinical sensitivity and specificity of commercial EIA and PCR STEC diagnostic tests, and summary receiver operator characteristic curves were constructed. We evaluated the certainty of evidence with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. RESULTS We identified 43 articles reflecting 25 260 specimens. Meta-analysis of EIA and PCR accuracy included 25 and 22 articles, respectively. STEC EIA pooled sensitivity and specificity were 0.681 (95% CI, 0.571-0.773; very low certainty of evidence) and 1.00 (95% CI, 0.998-1.00; moderate certainty of evidence), respectively. STEC PCR pooled sensitivity and specificity were 1.00 (95% CI, 0.904-1.00; low certainty of evidence) and 0.999 (95% CI, 0.997-0.999; low certainty of evidence), respectively. Certainty of evidence was downgraded because of high risk of bias. CONCLUSIONS PCR tests to identify the presence of STEC are more sensitive than EIA tests, with no meaningful loss of specificity. However, given the low certainty of evidence, our results may overestimate the difference in performance.
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Affiliation(s)
- Gillian A M Tarr
- Department of Pediatrics, University of Calgary, Calgary, AB, Canada
| | - Chu Yang Lin
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Ben Vandermeer
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | | | - Phillip I Tarr
- Department of Pediatrics, Washington University in St. Louis School of Medicine, St. Louis, MO
| | - Linda Chui
- Department of Laboratory Medicine and Pathology, University of Alberta and Alberta Precision Laboratories-ProvLab, Edmonton, AB, Canada
| | - Lisa Hartling
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Stephen B Freedman
- Sections of Pediatric Emergency Medicine and Gastroenterology, Department of Pediatrics, Alberta Children's Hospital and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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Development and Evaluation of a Novel VHH-Based Immunocapture Assay for High-Sensitivity Detection of Shiga Toxin Type 2 (Stx2) in Stool Samples. J Clin Microbiol 2020; 58:JCM.01566-19. [PMID: 31826960 DOI: 10.1128/jcm.01566-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 12/04/2019] [Indexed: 12/16/2022] Open
Abstract
Shiga toxin (Stx)-producing Escherichia coli (STEC) is the main cause of postdiarrheal hemolytic-uremic syndrome (HUS), a life-threatening clinical complication characterized by hemolytic anemia, thrombocytopenia, and acute renal failure that mainly affects children. A relevant feature of STEC strains is the production of Stx, and all of them express Stx1 and/or Stx2 regardless of the strain serotype. Therefore, Stx detection assays are considered the most suitable methods for the early detection of STEC infections. Single-domain antibodies from camelids (VHHs) exhibit several advantages in comparison with conventional antibodies, making them promising tools for diagnosis. In this work, we have exploited VHH technology for the development of an immunocapture assay for Stx2 detection. Thirteen anti-Stx2 VHHs previously obtained from a variable-domain repertoire library were selected and evaluated in 130 capture-detection pair combinations for Stx detection. Based on this analysis, two VHHs were selected and a double VHH-based biotin-streptavidin capture enzyme-linked immunosorbent assay (ELISA) with spectrophotometric detection was developed and optimized for Stx2 detection. This assay showed an excellent analytical and clinical sensitivity in both STEC culture supernatants and stool samples even higher than the sensitivity of a commercial ELISA. Furthermore, based on the analysis of stool samples, the VHH-based ELISA showed high correlation with stx 2 detection by PCR and a commercial rapid membrane-based immunoassay. The intrinsic properties of VHHs (high target affinity and specificity, stability, and ease of expression at high yields in recombinant bacteria) and their optimal performance for Stx detection make them attractive tools for the diagnosis of HUS related to STEC (STEC-HUS).
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Pohlentz G, Steil D, Rubin D, Mellmann A, Karch H, Müthing J. Pectin-derived neoglycolipids: Tools for differentiation of Shiga toxin subtypes and inhibitors of Shiga toxin-mediated cellular injury. Carbohydr Polym 2019; 212:323-333. [DOI: 10.1016/j.carbpol.2019.02.039] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 02/04/2019] [Accepted: 02/12/2019] [Indexed: 01/14/2023]
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Swoveland JL, Stewart LK, Eckmann MK, Gee R, Allen KJ, Vandegrift CM, Olson G, Kang MG, Tran ML, Melius E, Hiatt B, Gautom RK, Perez-Osorio AC. Laboratory Review of Foodborne Disease Investigations in Washington State 2007-2017. Foodborne Pathog Dis 2019; 16:513-523. [PMID: 30969140 PMCID: PMC6653799 DOI: 10.1089/fpd.2018.2592] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The Washington State Department of Health Public Health Laboratories (WAPHL) has tested 11,501 samples between 2007 and 2017 for a foodborne disease using a combination of identification, serotyping, and subtyping tools. During this period there were 8037 total clinical and environmental samples tested by pulsed-field gel electrophoresis (PFGE), including 512 foodborne disease clusters and 2176 PFGE patterns of Salmonella enterica subsp. enterica. There were 2446 Shiga toxin–producing Escherichia coli samples tested by PFGE, which included 158 foodborne disease clusters and 1174 PFGE patterns. There were 332 samples of Listeria monocytogenes tested by PFGE, including 35 foodborne disease clusters and 104 PFGE patterns. Sources linked to outbreaks included raw chicken, unpasteurized dairy products, various produce types, and undercooked beef among others. As next-generation sequencing (NGS) replaces PFGE, the impact of this transition is expected to be significant given the enhanced cluster detection power NGS brings. The measures presented here will be a reference baseline in future years.
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Affiliation(s)
- Jennifer L Swoveland
- 1 Public Health Laboratories, Washington State Department of Health, Shoreline, Washington
| | - Laurie K Stewart
- 2 Communicable Disease Epidemiology, Washington State Department of Health, Shoreline, Washington
| | - Mary Kaye Eckmann
- 1 Public Health Laboratories, Washington State Department of Health, Shoreline, Washington
| | - Raymond Gee
- 1 Public Health Laboratories, Washington State Department of Health, Shoreline, Washington
| | - Krisandra J Allen
- 2 Communicable Disease Epidemiology, Washington State Department of Health, Shoreline, Washington
| | - Calley M Vandegrift
- 1 Public Health Laboratories, Washington State Department of Health, Shoreline, Washington
| | - Gina Olson
- 1 Public Health Laboratories, Washington State Department of Health, Shoreline, Washington
| | - Mi-Gyeong Kang
- 1 Public Health Laboratories, Washington State Department of Health, Shoreline, Washington
| | - Michael L Tran
- 1 Public Health Laboratories, Washington State Department of Health, Shoreline, Washington
| | - Elizabeth Melius
- 2 Communicable Disease Epidemiology, Washington State Department of Health, Shoreline, Washington
| | - Brian Hiatt
- 1 Public Health Laboratories, Washington State Department of Health, Shoreline, Washington
| | - Romesh K Gautom
- 1 Public Health Laboratories, Washington State Department of Health, Shoreline, Washington
| | - Ailyn C Perez-Osorio
- 1 Public Health Laboratories, Washington State Department of Health, Shoreline, Washington
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Sánchez S, Llorente MT, Ramiro R, Herrera-León L, Herrera-León S. Evaluation of the SHIGA TOXIN QUIK CHEK after overnight enrichment as screening tool for Shiga toxin-producing Escherichia coli detection in human fecal samples. Diagn Microbiol Infect Dis 2019; 94:218-222. [PMID: 30885395 DOI: 10.1016/j.diagmicrobio.2019.01.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 01/17/2019] [Accepted: 01/20/2019] [Indexed: 12/18/2022]
Abstract
We evaluated the SHIGA TOXIN QUIK CHEK (STQC) on its suitability for Shiga toxin-producing Escherichia coli (STEC) testing on human fecal samples after overnight enrichment. Our in-house PCR-based protocol for STEC detection was used as the standard for comparison. STQC detected all described Shiga toxin subtypes with the only exception of Stx2f. In comparison to PCR, STQC performed with an overall sensitivity of 55.4%, specificity of 100.0%, positive predictive value of 100.0%, negative predictive value of 73.0%, infinite positive likelihood ratio, and negative likelihood ratio of 0.45. We conclude that STQC may not be considered a suitable screening tool for STEC detection in human fecal samples, although it could be useful for laboratories where PCR is not a routine tool for STEC screening yet, subject to the confirmation of negative samples by a reference laboratory with full diagnostic capabilities.
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Affiliation(s)
- Sergio Sánchez
- Reference and Research Laboratory of Food and Waterborne Bacterial Infections, National Center for Microbiology, Institute of Health Carlos III, Majadahonda, Madrid, Spain.
| | - María Teresa Llorente
- Reference and Research Laboratory of Food and Waterborne Bacterial Infections, National Center for Microbiology, Institute of Health Carlos III, Majadahonda, Madrid, Spain
| | - Raquel Ramiro
- Reference and Research Laboratory of Food and Waterborne Bacterial Infections, National Center for Microbiology, Institute of Health Carlos III, Majadahonda, Madrid, Spain
| | - Laura Herrera-León
- Reference and Research Laboratory of Food and Waterborne Bacterial Infections, National Center for Microbiology, Institute of Health Carlos III, Majadahonda, Madrid, Spain
| | - Silvia Herrera-León
- Reference and Research Laboratory of Food and Waterborne Bacterial Infections, National Center for Microbiology, Institute of Health Carlos III, Majadahonda, Madrid, Spain
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8
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Steil D, Pohlentz G, Legros N, Mormann M, Mellmann A, Karch H, Müthing J. Combining Mass Spectrometry, Surface Acoustic Wave Interaction Analysis, and Cell Viability Assays for Characterization of Shiga Toxin Subtypes of Pathogenic Escherichia coli Bacteria. Anal Chem 2018; 90:8989-8997. [PMID: 29939014 DOI: 10.1021/acs.analchem.8b01189] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Shiga toxin (Stx)-producing Escherichia coli (STEC) and enterohemorrhagic E. coli (EHEC) as a human pathogenic subgroup of STEC are characterized by releasing Stx AB5-toxin as the major virulence factor. Worldwide disseminated EHEC strains cause sporadic infections and outbreaks in the human population and swine pathogenic STEC strains represent greatly feared pathogens in pig breeding and fattening plants. Among the various Stx subtypes, Stx1a and Stx2a are of eminent clinical importance in human infections being associated with life-threatening hemorrhagic colitis and hemolytic uremic syndrome, whereas Stx2e subtype is associated with porcine edema disease with a generalized fatal outcome for the animals. Binding toward the glycosphingolipid globotriaosylceramide (Gb3Cer) is a common feature of all Stx subtypes analyzed so far. Here, we report on the development of a matched strategy combining (i) miniaturized one-step affinity purification of native Stx subtypes from culture supernatant of bacterial wild-type strains using Gb3-functionalized magnetic beads, (ii) structural analysis and identification of Stx holotoxins by electrospray ionization ion mobility mass spectrometry (ESI MS), (iii) functional Stx-receptor real-time interaction analysis employing the surface acoustic wave (SAW) technology, and (iv) Vero cell culture assays for determining Stx-caused cytotoxic effects. Structural investigations revealed diagnostic tryptic peptide ions for purified Stx1a, Stx2a, and Stx2e, respectively, and functional analysis resulted in characteristic binding kinetics of each Stx subtype. Cytotoxicity studies revealed differing toxin-mediated cell damage ranked with Stx1a > Stx2a > Stx2e. Collectively, this matched procedure represents a promising clinical application for the characterization of life-endangering Stx subtypes at the protein level.
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Affiliation(s)
- Daniel Steil
- Institute for Hygiene , University of Münster , Robert-Koch-Strasse 41 , D-48149 Münster , Germany
| | - Gottfried Pohlentz
- Institute for Hygiene , University of Münster , Robert-Koch-Strasse 41 , D-48149 Münster , Germany
| | - Nadine Legros
- Institute for Hygiene , University of Münster , Robert-Koch-Strasse 41 , D-48149 Münster , Germany
| | - Michael Mormann
- Institute for Hygiene , University of Münster , Robert-Koch-Strasse 41 , D-48149 Münster , Germany
| | - Alexander Mellmann
- Institute for Hygiene , University of Münster , Robert-Koch-Strasse 41 , D-48149 Münster , Germany.,Interdisciplinary Center for Clinical Research (IZKF) Münster , Domagkstrasse 3 , D-48149 Münster , Germany
| | - Helge Karch
- Institute for Hygiene , University of Münster , Robert-Koch-Strasse 41 , D-48149 Münster , Germany.,Interdisciplinary Center for Clinical Research (IZKF) Münster , Domagkstrasse 3 , D-48149 Münster , Germany
| | - Johannes Müthing
- Institute for Hygiene , University of Münster , Robert-Koch-Strasse 41 , D-48149 Münster , Germany.,Interdisciplinary Center for Clinical Research (IZKF) Münster , Domagkstrasse 3 , D-48149 Münster , Germany
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Freedman SB, Grisaru S, Xie J, Samuel S, Dixon A, Plint AC, Schnadower D. Management of Shiga toxin producing Escherichia coli-infected children: A multi-national, multi-specialty survey. J Paediatr Child Health 2018; 54:390-397. [PMID: 29111613 DOI: 10.1111/jpc.13778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 09/03/2017] [Indexed: 12/19/2022]
Abstract
AIM Research has highlighted the potential role that hydration status may play in predicting outcomes in Shiga toxin-producing Escherichia coli (STEC)-infected children. Because little is known about the management of STEC-infected children in the pre-haemolytic uremic syndrome phase, we compared paediatric emergency medicine and nephrologist-stated management approaches to STEC-infected children. METHODS Members of the Pediatric Emergency Research Canada (PERC; n = 228), the Pediatric Emergency Medicine Collaborative Research Committee (PEM CRC; n = 221) and the Canadian Association of Pediatric Nephrologists (CAPN; n = 66) were surveyed. Five individualised e-mail requests containing a link to a 42-question web-based survey were sent to eligible participants. RESULTS Of 496 potentially eligible participants, 276 (56%) submitted complete survey responses. In children with classic features of STEC infection, baseline haemoglobin/haematocrit is obtained by 54% of PERC, 41% of PEM CRC and 83% of CAPN members (P < 0.001), and baseline renal function is obtained by 51% of PERC, 38% of PEM CRC and 83% of CAPN members (P < 0.001). Intravenous fluids are more often recommended by nephrologists (28%) compared with PEM physicians (7%), P < 0.001. In children with known E. coli O157:H7 infection, nephrologists more commonly recommend clinical follow-up (P = 0.003), complete blood counts (P < 0.001) and renal function/electrolyte testing (P < 0.001). Intravenous fluid administration and admission are more commonly recommended by nephrologists (P = 0.03 and P < 0.001, respectively). CONCLUSION Compared with paediatric nephrologists, paediatric emergency medicine physicians are less likely to perform baseline and follow-up blood tests and to administer intravascular volume expansion in children at risk of, and with confirmed, E. coli O157:H7 infection.
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Affiliation(s)
- Stephen B Freedman
- Section of Pediatric Emergency Medicine and Gastroenterology, Alberta Children's Hospital, Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Silviu Grisaru
- Section of Pediatric Nephrology, Alberta Children's Hospital, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Jianling Xie
- Section of Pediatric Emergency Medicine, Alberta Children's Hospital, University of Calgary, Calgary, Alberta, Canada
| | - Susan Samuel
- Section of Pediatric Nephrology, Alberta Children's Hospital, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Andrew Dixon
- Division of Pediatric Emergency Medicine, Stollery Children's Hospital, Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Amy C Plint
- Division of Pediatric Emergency Medicine, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada
| | - David Schnadower
- Division of Pediatric Emergency Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
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A Rapid Immunoassay for Detection of Shiga Toxin-Producing Escherichia coli Directly from Human Fecal Samples and Its Performance in Detection of Toxin Subtypes. J Clin Microbiol 2016; 54:3056-3063. [PMID: 27733635 PMCID: PMC5121400 DOI: 10.1128/jcm.01785-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 10/05/2016] [Indexed: 12/04/2022] Open
Abstract
Fecal samples (n = 531) submitted to a regional clinical laboratory during a 6-month period were tested for the presence of Shiga toxin using both a Vero cell cytotoxicity assay and the Shiga Toxin Quik Chek test (STQC), a rapid membrane immunoassay. Testing the samples directly (without culture), 9 positives were identified by the Vero cell assay, all of which were also detected by the STQC. The correlation between the two assays was 100%. Not all of the identified positive samples were detected when fecal broth cultures were tested. By testing broth cultures of characterized isolates representing all described Shiga toxin subtypes, the STQC detected all subtypes. Levels of induction of toxin production by ciprofloxacin differed among the strains tested, with more toxin induction seen in strains harboring Stx2 phages than in those harboring Stx1 phages.
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