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Silwamba S, Chilyabanyama ON, Liswaniso F, Chisenga CC, Chilengi R, Dougan G, Kwenda G, Chakraborty S, Simuyandi M. Field evaluation of a novel, rapid diagnostic assay, and molecular epidemiology of enterotoxigenic E. coli among Zambian children presenting with diarrhea. PLoS Negl Trop Dis 2022; 16:e0010207. [PMID: 35930612 PMCID: PMC9385031 DOI: 10.1371/journal.pntd.0010207] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 08/17/2022] [Accepted: 07/22/2022] [Indexed: 11/24/2022] Open
Abstract
Background Enterotoxigenic Escherichia coli (ETEC) is one of the top aetiologic agents of diarrhea in children under the age of 5 in low-middle income countries (LMICs). The lack of point of care diagnostic tools for routine ETEC diagnosis results in limited data regarding the actual burden and epidemiology in the endemic areas. We evaluated performance of the novel Rapid LAMP based Diagnostic Test (RLDT) for detection of ETEC in stool as a point of care diagnostic assay in a resource-limited setting. Methods We conducted a cross-sectional study of 324 randomly selected stool samples from children under 5 presenting with moderate to severe diarrhea (MSD). The samples were collected between November 2012 to September 2013 at selected health facilities in Zambia. The RLDT was evaluated by targeting three ETEC toxin genes [heat labile toxin (LT) and heat stable toxins (STh and STp)]. Quantitative PCR was used as the “gold standard” to evaluate the diagnostic sensitivity and specificity of RLDT for detection of ETEC. We additionally described the prevalence and seasonality of ETEC. Results The study included 324 participants, 50.6% of which were female. The overall prevalence of ETEC was 19.8% by qPCR and 19.4% by RLDT. The children between 12 to 59 months had the highest prevalence of 22%. The study determined ETEC toxin distribution was LT 28/321(9%), ST 18/321(6%) and LT/ST 16/321(5%). The sensitivity and specificity of the RLDT compared to qPCR using a Ct 35 as the cut-off, were 90.7% and 97.5% for LT, 85.2% and 99.3% for STh and 100% and 99.7% for STp, respectively. Conclusion The results of this study suggest that RLDT is sufficiently sensitive and specific and easy to implement in the endemic countries. Being rapid and simple, the RLDT also presents as an attractive tool for point-of-care testing at the health facilities and laboratories in the resource-limited settings. ETEC is one of the top causes of diarrheal diseases in low and middle income countries. The advancement of molecular diagnosis has made it possible to accurately detect ETEC in endemic areas. However, the complexity, infrastructure and cost implication of these tests has made it a challenge to routinely incorporate them in health facilities in endemic settings. The ETEC RLDT is a simple and cost-effective molecular tool that can be used to screen for ETEC in resource limited settings. Here, we described the performance of the RLDT against a qPCR as the gold standard. Our findings showed that the ETEC RLDT performs comparable to the qPCR and would be a suitable screening tool in health facilities in recourse limited settings.
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Affiliation(s)
- Suwilanji Silwamba
- Enteric Diseases and Vaccines Research Unit, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
- Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka, Zambia
| | - Obvious N. Chilyabanyama
- Enteric Diseases and Vaccines Research Unit, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Fraser Liswaniso
- Enteric Diseases and Vaccines Research Unit, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Caroline C. Chisenga
- Enteric Diseases and Vaccines Research Unit, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Roma Chilengi
- Enteric Diseases and Vaccines Research Unit, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Gordon Dougan
- Cambridge Institute for Therapeutic Immunology and Infectious Disease, University of Cambridge, Cambridge, United Kingdom
| | - Geoffrey Kwenda
- Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka, Zambia
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail: (SC); (MS)
| | - Michelo Simuyandi
- Enteric Diseases and Vaccines Research Unit, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
- * E-mail: (SC); (MS)
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2
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Tisdale MD, Tribble DR, Mitra I, Telu K, Kuo HC, Fraser JA, Liu J, Houpt ER, Riddle MS, Tilley DH, Kunz AN, Yun HC, Geist CC, Lalani T. TaqMan Array Card testing of participant-collected stool smears to determine the pathogen-specific epidemiology of travellers' diarrhoea†. J Travel Med 2022; 29:6365984. [PMID: 34494100 PMCID: PMC8763119 DOI: 10.1093/jtm/taab138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/17/2021] [Accepted: 08/19/2021] [Indexed: 11/13/2022]
Abstract
BACKGROUND We assessed the compliance with self-collection of stool smears on Whatman® FTA® Elute Card (FTA Card) and detection of travellers' diarrhoea (TD)-associated pathogens by using a quantitative Polymerase Chain Reaction (PCR) assay [customized TaqMan® array card (TAC)] in a prospective, observational cohort of travellers. METHODS Enrolled travellers documented symptoms on a travel diary and collected an FTA Card during a diarrhoeal episode, or at the end of travel if they remained asymptomatic. TAC testing was performed on FTA Cards from TD cases and 1:1 matched asymptomatic controls and 1:1 matched loose stool cases that did not meet TD criteria. Odds ratios were used to determine the association between detected pathogens and TD. RESULTS Of 2456 travellers, 484 (19.7%) completed an illness diary and met TD criteria, and 257 (53.1%) collected an FTA Card during the TD episode. FTA Cards were stored for a median of 2 years at room temperature (IQR: 1-4 years) before extraction and testing. The overall TAC detection rate in TD cases was 58.8% (95% CI: 52.5-64.8). Enterotoxigenic Escherichia coli was the most common pathogen in TD cases (26.8%), and 3.5% of samples were positive for norovirus. The odds of detecting TD-associated pathogens in 231 matched cases and asymptomatic controls were 5.4 (95% CI: 3.6-8.1) and 2.0 (95% CI: 1.1-3.7) in 121 matched TD and loose stool cases (P < 0.05). Enteroaggregative E. coli was the most common pathogen detected in asymptomatic controls and loose stool cases. Detection of diarrhoeagenic E. coli, Shigella/enteroinvasive E. coli and Campylobacter spp. was significantly associated with TD. CONCLUSION FTA Cards are a useful adjunct to traditional stool collection methods for evaluating the pathogen-specific epidemiology of TD in austere environments. Qualitative detection of pathogens was associated with TD. Measures to improve compliance and quality of FTA Card collection with decreased storage duration may further optimize detection.
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Affiliation(s)
- Michele D Tisdale
- To whom correspondence should be addressed. Infectious Disease & Travel Clinic, Building 3, 1st Floor, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA.
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3
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Medeiros PHQS, Bolick DT, Ledwaba SE, Kolling GL, Costa DVS, Oriá RB, Lima AÂM, Barry EM, Guerrant RL. A bivalent vaccine confers immunogenicity and protection against Shigella flexneri and enterotoxigenic Escherichia coli infections in mice. NPJ Vaccines 2020; 5:30. [PMID: 32257392 PMCID: PMC7101394 DOI: 10.1038/s41541-020-0180-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 03/06/2020] [Indexed: 12/12/2022] Open
Abstract
Vaccine studies for Shigella flexneri and enterotoxigenic Escherichia coli have been impaired by the lack of optimal animal models. We used two murine models to show that a S. flexneri 2a bivalent vaccine (CVD 1208S-122) expressing enterotoxigenic Escherichia coli colonization factor antigen-I (CFA/I) and the binding subunits A2 and B of heat labile-enterotoxin (LTb) is immunogenic and protects against weight loss and diarrhea. These findings document the immunogenicity and pre-clinical efficacy effects of CVD 1208S-122 vaccine and suggest that further work can help elucidate relevant immune responses and ultimately its clinical efficacy in humans.
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Affiliation(s)
- Pedro Henrique Q S Medeiros
- 1Center for Global Health and Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA USA.,2Institute of Biomedicine, Federal University of Ceará, Fortaleza, CE Brazil
| | - David T Bolick
- 1Center for Global Health and Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA USA
| | - Solanka E Ledwaba
- 1Center for Global Health and Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA USA.,3Department of Microbiology, University of Venda, Thohoyandou, Limpopo province South Africa
| | - Glynis L Kolling
- 1Center for Global Health and Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA USA
| | - Deiziane V S Costa
- 1Center for Global Health and Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA USA.,2Institute of Biomedicine, Federal University of Ceará, Fortaleza, CE Brazil
| | - Reinaldo B Oriá
- 1Center for Global Health and Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA USA.,2Institute of Biomedicine, Federal University of Ceará, Fortaleza, CE Brazil
| | - Aldo Ângelo M Lima
- 2Institute of Biomedicine, Federal University of Ceará, Fortaleza, CE Brazil
| | - Eileen M Barry
- 4Center for Vaccine Development and Global Health, University of Maryland, Baltimore, MD USA
| | - Richard L Guerrant
- 1Center for Global Health and Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA USA
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4
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Yang B, Fan Y, Li Y, Yan J, Fang X, Kong J. Rapid and simultaneous analysis of twelve virulence factor genes by a microfluidic-CFPA chip for identifying diarrheagenic Escherichia coli. Analyst 2020; 145:3814-3821. [DOI: 10.1039/c9an02572c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An integrated microfluidic system based on circular fluorescent probe-mediated isothermal nucleic acid amplification for identification of five diarrheagenic Escherichia coli strains has been developed.
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Affiliation(s)
- Bin Yang
- Department of Chemistry and Institutes of Biomedical Sciences
- Fudan University
- Shanghai
- PR China
| | - Yiling Fan
- Shanghai Institute for Food and Drug Control
- Shanghai 201203
- PR China
| | - Yang Li
- Shanghai Suxin Biotechnology Co. Ltd
- Shanghai
- PR China
| | - Jun Yan
- Shanghai Suxin Biotechnology Co. Ltd
- Shanghai
- PR China
| | - Xueen Fang
- Department of Chemistry and Institutes of Biomedical Sciences
- Fudan University
- Shanghai
- PR China
| | - Jilie Kong
- Department of Chemistry and Institutes of Biomedical Sciences
- Fudan University
- Shanghai
- PR China
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5
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Grasselli G, Scaravilli V, Alagna L, Bombino M, De Falco S, Bandera A, Abbruzzese C, Patroniti N, Gori A, Pesenti A. Gastrointestinal colonization with multidrug-resistant Gram-negative bacteria during extracorporeal membrane oxygenation: effect on the risk of subsequent infections and impact on patient outcome. Ann Intensive Care 2019; 9:141. [PMID: 31853672 PMCID: PMC6920277 DOI: 10.1186/s13613-019-0615-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 12/05/2019] [Indexed: 01/12/2023] Open
Abstract
Background In ICU patients, digestive tract colonization by multidrug-resistant (MDR) Gram-negative (G−) bacteria is a significant risk factor for the development of infections. In patients undergoing extracorporeal membrane oxygenation (ECMO), colonization by MDR bacteria and risk of subsequent nosocomial infections (NIs) have not been studied yet. The aim of this study is to evaluate the incidence, etiology, risk factors, impact on outcome of gastrointestinal colonization by MDR G− bacteria, and risk of subsequent infections in patients undergoing ECMO. Methods This is a retrospective analysis of prospectively collected data: 105 consecutive patients, treated with ECMO, were admitted to the ICU of an Italian tertiary referral center (San Gerardo Hospital, Monza, Italy) from January 2010 to November 2015. Rectal swabs for MDR G− bacteria were cultured at admission and twice a week. Only colonization and NIs by MDR G− bacteria were analyzed. Results Ninety-one included patients [48.5 (37–56) years old, 63% male, simplified acute physiology score II 37 (32–47)] underwent peripheral ECMO (87% veno-venous) for medical indications (79% ARDS). Nineteen (21%) patients were colonized by MDR G− bacteria. Male gender (OR 4.03, p = 0.029) and duration of mechanical ventilation (MV) before ECMO > 3 days (OR 3.57, p = 0.014) were associated with increased risk of colonization. Colonized patients had increased odds of infections by the colonizing germs (84% vs. 29%, p < 0.001, OR 12.9), longer ICU length of stay (LOS) (43 vs. 24 days, p = 0.002), MV (50 vs. 22 days, p < 0.001) and ECMO (28 vs. 12 days, p < 0.001), but did not have higher risk of death (survival rate 58% vs. 67%, p = 0.480, OR 0.68). Infected patients had almost halved ICU survival (46% vs. 78%, p < 0.001, OR 4.11). Conclusions In patients undergoing ECMO for respiratory and/or circulatory failure, colonization by MDR G− bacteria is frequent and associated with more the tenfold odds for subsequent infection. Those infections are associated with an increased risk of death.
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Affiliation(s)
- Giacomo Grasselli
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milan, MI, Italy. .,Department of Pathophysiology and Transplantation, University of Milan, Milan, MI, Italy.
| | - Vittorio Scaravilli
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milan, MI, Italy
| | - Laura Alagna
- Infectious Diseases Unit, IRCCS Ca' Granda Ospedale Maggiore Policlinico Foundation, Milan, Italy
| | - Michela Bombino
- Department of Anesthesia, Critical Care and Emergency, ASST Monza San Gerardo Hospital, Monza, MB, Italy
| | - Stefano De Falco
- Department of Pathophysiology and Transplantation, University of Milan, Milan, MI, Italy
| | - Alessandra Bandera
- Department of Pathophysiology and Transplantation, University of Milan, Milan, MI, Italy.,Infectious Diseases Unit, IRCCS Ca' Granda Ospedale Maggiore Policlinico Foundation, Milan, Italy
| | - Chiara Abbruzzese
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milan, MI, Italy
| | - Nicolò Patroniti
- Anaesthesia and Intensive Care, San Martino Policlinico Hospital, IRCCS for Oncology, Genoa, Italy.,Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy
| | - Andrea Gori
- Department of Pathophysiology and Transplantation, University of Milan, Milan, MI, Italy.,Infectious Diseases Unit, IRCCS Ca' Granda Ospedale Maggiore Policlinico Foundation, Milan, Italy
| | - Antonio Pesenti
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milan, MI, Italy.,Department of Pathophysiology and Transplantation, University of Milan, Milan, MI, Italy
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6
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Tisdale MD, Tribble DR, Telu K, Fraser JA, Connor P, Philip C, Odundo E, Reyes F, Simons MP, Swierczewski B, Lizewski S, Liu J, Houpt E, Riddle MS, Lalani T. A Comparison of Stool Enteropathogen Detection by Semiquantitative PCR in Adults With Acute Travelers' Diarrhea Before and 3 Weeks After Successful Antibiotic Treatment. Open Forum Infect Dis 2019; 6:ofz187. [PMID: 31123694 PMCID: PMC6524828 DOI: 10.1093/ofid/ofz187] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 04/24/2019] [Indexed: 12/24/2022] Open
Abstract
We evaluated stool enteropathogen detection by semiquantitative polymerase chain reaction (PCR) in 108 subjects with travelers’ diarrhea before and 3 weeks after treatment. Stool samples from 21 subjects were positive for the same pathogen species at both visits. We discuss factors that should be considered when interpreting stool PCR data after treatment.
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Affiliation(s)
- Michele D Tisdale
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, Maryland.,Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland.,Division of Infectious Diseases, Naval Medical Center, Portsmouth, Virginia
| | - David R Tribble
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, Maryland
| | - Kalyani Telu
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, Maryland.,Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland
| | - Jamie A Fraser
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, Maryland.,Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland
| | - Patrick Connor
- Academic Department of Military Medicine, Royal Centre for Defence Medicine, Birmingham, UK
| | - Cliff Philip
- United States Army Medical Research Unit Kenya, Kericho, Kenya
| | | | - Faviola Reyes
- Joint Task Force Bravo, Soto Cano Air Base, Comayagua, Honduras
| | - Mark P Simons
- Naval Medical Research Center, Silver Spring, Maryland
| | | | | | - Jie Liu
- University of Virginia, Charlottesville, Virginia
| | - Eric Houpt
- University of Virginia, Charlottesville, Virginia
| | - Mark S Riddle
- F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda, Maryland
| | - Tahaniyat Lalani
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, Maryland.,Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland.,Division of Infectious Diseases, Naval Medical Center, Portsmouth, Virginia
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7
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Tsai K, Simiyu S, Mumma J, Aseyo RE, Cumming O, Dreibelbis R, Baker KK. Enteric Pathogen Diversity in Infant Foods in Low-Income Neighborhoods of Kisumu, Kenya. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16030506. [PMID: 30759722 PMCID: PMC6388216 DOI: 10.3390/ijerph16030506] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 02/05/2019] [Accepted: 02/07/2019] [Indexed: 01/01/2023]
Abstract
Pediatric diarrheal disease remains the second most common cause of preventable illness and death among children under the age of five, especially in low and middle-income countries (LMICs). However, there is limited information regarding the role of food in pathogen transmission in LMICs. For this study, we examined the frequency of enteric pathogen occurrence and co-occurrence in 127 infant weaning foods in Kisumu, Kenya, using a multi-pathogen PCR diagnostic tool, and assessed household food hygiene risk factors for contamination. Bacterial, viral, and protozoan enteric pathogen DNA and RNA were detected in 62% of the infant weaning food samples collected, with 37% of foods containing more than one pathogen type. Multivariable generalized linear mixed model analysis indicated type of infant food best explained the presence and diversity of enteric pathogens in infant food, while most household food hygiene risk factors considered in this study were not significantly associated with pathogen contamination. Specifically, cow’s milk was significantly more likely to contain a pathogen (adjusted risk ratio = 14.4; 95% confidence interval (CI) 1.78–116.1) and more likely to have higher number of enteric pathogen species (adjusted risk ratio = 2.35; 95% CI 1.67–3.29) than porridge. Our study demonstrates that infants in this low-income urban setting are frequently exposed to diarrhoeagenic pathogens in food and suggests that interventions are needed to prevent foodborne transmission of pathogens to infants.
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Affiliation(s)
- Kevin Tsai
- Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA 52246, USA.
| | - Sheillah Simiyu
- Center of Research, Great Lakes University of Kisumu, Kisumu 40100, Kenya.
| | - Jane Mumma
- Center of Research, Great Lakes University of Kisumu, Kisumu 40100, Kenya.
| | - Rose Evalyne Aseyo
- Center of Research, Great Lakes University of Kisumu, Kisumu 40100, Kenya.
| | - Oliver Cumming
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
| | - Robert Dreibelbis
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
| | - Kelly K Baker
- Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA 52246, USA.
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8
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Lalani T, Tisdale MD, Liu J, Mitra I, Philip C, Odundo E, Reyes F, Simons MP, Fraser JA, Hutley E, Connor P, Swierczewski BE, Houpt E, Tribble DR, Riddle MS. Comparison of stool collection and storage on Whatman FTA Elute cards versus frozen stool for enteropathogen detection using the TaqMan Array Card PCR assay. PLoS One 2018; 13:e0202178. [PMID: 30165370 PMCID: PMC6117160 DOI: 10.1371/journal.pone.0202178] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 07/30/2018] [Indexed: 12/27/2022] Open
Abstract
The use of Polymerase Chain Reaction (PCR) assays for pathogen detection in travelers' diarrhea (TD) field studies is limited by the on-site processing and storage requirements for fecal specimens. The objectives of this investigation were to i) characterize the pathogen distribution in deployed military personnel with TD using the TaqMan® Array Card PCR (TAC) on frozen stool and diarrheal smears on Whatman FTA Elute cards (FTA cards), and to ii) compare TAC detection of enteropathogen targets using smeared FTA cards and frozen stool, using TAC on frozen stool as the 'reference standard'. Stool samples, obtained from active duty personnel with acute TD enrolled in a field trial, were smeared onto FTA cards and stored at room temperature. A corresponding aliquot of stool was frozen in a cryovial. FTA cards and frozen stool samples were tested at a central lab, using a customized TAC for detection of TD pathogens. 187 paired frozen stool samples and smeared FTA cards were stored for a median of 712 days (IQR 396-750) before testing. Overall detection rates were 78.6% for frozen stool and 73.2% for FTA cards. Diarrheagenic Escherichia coli were the most common bacteria identified. Using the TAC results on frozen stool as the reference, the overall sensitivity and specificity of TAC on FTA cards was 72.9% and 98.0% respectively. TAC on FTA cards demonstrated a decrease in sensitivity with increasing frozen stool quantification cycle (Cq) (90.0% in FTA cards with a corresponding frozen stool Cq < 30, and 72.9% in samples with a corresponding frozen stool Cq < 35). Our findings support the use and further development of FTA cards in combination with a quantitative PCR assay for enteropathogen detection in TD field studies.
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Affiliation(s)
- Tahaniyat Lalani
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, MD, United States of America
- Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States of America
- Division of Infectious Diseases, Naval Medical Center, Portsmouth, VA, United States of America
| | - Michele D. Tisdale
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, MD, United States of America
- Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States of America
- Division of Infectious Diseases, Naval Medical Center, Portsmouth, VA, United States of America
| | - Jie Liu
- University of Virginia, Charlottesville, VA, United States of America
| | - Indrani Mitra
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, MD, United States of America
- Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States of America
| | - Cliff Philip
- United States Army Medical Research Unit Kenya, Kericho, Kenya
| | | | - Faviola Reyes
- Joint Task Force Bravo, Soto Cano Air Base, Honduras
| | - Mark P. Simons
- Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Jamie A. Fraser
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, MD, United States of America
- Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States of America
| | - Emma Hutley
- Department of Military Medicine, Royal Centre for Defense Medicine, Birmingham, United Kingdom
| | - Patrick Connor
- Department of Military Medicine, Royal Centre for Defense Medicine, Birmingham, United Kingdom
| | | | - Eric Houpt
- University of Virginia, Charlottesville, VA, United States of America
| | - David R. Tribble
- Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Rockville, MD, United States of America
| | - Mark S. Riddle
- F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda, MD, United States of America
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9
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Begum YA, Rydberg HA, Thorell K, Kwak YK, Sun L, Joffré E, Qadri F, Sjöling Å. In Situ Analyses Directly in Diarrheal Stool Reveal Large Variations in Bacterial Load and Active Toxin Expression of Enterotoxigenic Escherichiacoli and Vibrio cholerae. mSphere 2018; 3:e00517-17. [PMID: 29404412 PMCID: PMC5784243 DOI: 10.1128/msphere.00517-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 12/27/2017] [Indexed: 11/20/2022] Open
Abstract
The bacterial pathogens enterotoxigenic Escherichia coli (ETEC) and Vibrio cholerae are major causes of diarrhea. ETEC causes diarrhea by production of the heat-labile toxin (LT) and heat-stable toxins (STh and STp), while V. cholerae produces cholera toxin (CT). In this study, we determined the occurrence and bacterial doses of the two pathogens and their respective toxin expression levels directly in liquid diarrheal stools of patients in Dhaka, Bangladesh. By quantitative culture and real-time quantitative PCR (qPCR) detection of the toxin genes, the two pathogens were found to coexist in several of the patients, at concentrations between 102 and 108 bacterial gene copies per ml. Even in culture-negative samples, gene copy numbers of 102 to 104 of either ETEC or V. cholerae toxin genes were detected by qPCR. RNA was extracted directly from stool, and gene expression levels, quantified by reverse transcriptase qPCR (RT-qPCR), of the genes encoding CT, LT, STh, and STp showed expression of toxin genes. Toxin enzyme-linked immunosorbent assay (ELISA) confirmed active toxin secretion directly in the liquid diarrhea. Analysis of ETEC isolates by multiplex PCR, dot blot analysis, and genome sequencing suggested that there are genetic ETEC profiles that are more commonly found as dominating single pathogens and others that are coinfectants with lower bacterial loads. The ETEC genomes, including assembled genomes of dominating ETEC isolates expressing LT/STh/CS5/CS6 and LT/CS7, are provided. In addition, this study highlights an emerging important ETEC strain expressing LT/STp and the novel colonization factor CS27b. These findings have implications for investigations of pathogenesis as well as for vaccine development. IMPORTANCE The cause of diarrheal disease is usually determined by screening for several microorganisms by various methods, and sole detection is used to assign the agent as the cause of disease. However, it has become increasingly clear that many infections are caused by coinfections with several pathogens and that the dose of the infecting pathogen is important. We quantified the absolute numbers of enterotoxigenic E. coli (ETEC) and Vibrio cholerae directly in diarrheal fluid. We noted several events where both pathogens were found but also a large dose dependency. In three samples, we found ETEC as the only pathogen sought for. These isolates belonged to globally distributed ETEC clones and were the dominating species in stool with active toxin expression. This suggests that certain superior virulent ETEC lineages are able to outcompete the gut microbiota and be the sole cause of disease and hence need to be specifically monitored.
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Affiliation(s)
- Yasmin Ara Begum
- International Centre for Diarrhoeal Disease Research, Bangladesh, Centre for Health and Population Research, Dhaka, Bangladesh
| | - Hanna A. Rydberg
- Department of Microbiology, Tumor and Cell Biology, Centre for Translational Microbiome Research (CTMR), Karolinska Institutet, Stockholm, Sweden
| | - Kaisa Thorell
- Department of Microbiology, Tumor and Cell Biology, Centre for Translational Microbiome Research (CTMR), Karolinska Institutet, Stockholm, Sweden
| | - Young-Keun Kwak
- Department of Microbiology, Tumor and Cell Biology, Centre for Translational Microbiome Research (CTMR), Karolinska Institutet, Stockholm, Sweden
| | - Lei Sun
- Department of Microbiology, Tumor and Cell Biology, Centre for Translational Microbiome Research (CTMR), Karolinska Institutet, Stockholm, Sweden
| | - Enrique Joffré
- Department of Microbiology, Tumor and Cell Biology, Centre for Translational Microbiome Research (CTMR), Karolinska Institutet, Stockholm, Sweden
| | - Firdausi Qadri
- International Centre for Diarrhoeal Disease Research, Bangladesh, Centre for Health and Population Research, Dhaka, Bangladesh
| | - Åsa Sjöling
- Department of Microbiology, Tumor and Cell Biology, Centre for Translational Microbiome Research (CTMR), Karolinska Institutet, Stockholm, Sweden
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
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