| 1. |
- Mansour, A., et al.
(author)
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Diarrhea Burden Due to Natural Infection with Enterotoxigenic Escherichia coli in a Birth Cohort in a Rural Egyptian Community
- 2014
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In: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 52:7, s. 2595-2603
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Journal article (peer-reviewed)abstract
- Enterotoxigenic Escherichia coli (ETEC) is commonly associated with diarrhea in Egyptian children. Children less than 3 years old in Abu Homos, Egypt, had approximately five diarrheal episodes per child every year, and at least one of these episodes was due to ETEC. The epidemiology of ETEC diarrhea among children living in a rural Egyptian community was further evaluated in this study. Between January 2004 and April 2007, 348 neonates were enrolled and followed for 2 years. Children were visited twice weekly, and a stool sample was obtained every 2 weeks regardless of symptomatology. A stool sample was obtained whenever a child had diarrhea. From the routine stool culture, five E. coli-like colonies were selected and screened for heat-labile and heat-stable toxins by GM1 enzyme-linked immunosorbent assay (ELISA) and further typed for colonization factor antigens by dot blot assay. Incidence of ETEC infection was estimated among children with diarrhea (symptomatic) and without diarrhea (asymptomatic). Incidence of diarrhea and ETEC-associated diarrhea was 7.8 and 1.48 per child-year, respectively. High risk of repeated ETEC diarrhea was associated with being over 6 months of age, warm season, male gender, and crowded sleeping conditions. Exclusive breast-feeding was protective for repeated ETEC infection. ETEC-associated diarrhea remains common among children living in the Nile Delta. The protective role of breast-feeding demonstrates the importance of promoting exclusive breast-feeding during, at least, the first 6 months of life.
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| 2. |
- Mansour, A., et al.
(author)
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Pathogenicity and Phenotypic Characterization of Enterotoxigenic Escherichia coli Isolates from a Birth Cohort of Children in Rural Egypt
- 2014
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In: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 52:2, s. 587-591
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Journal article (peer-reviewed)abstract
- Enterotoxigenic Escherichia coli (ETEC) has consistently been the predominant bacterial cause of diarrhea in many birth cohort-and hospital-based studies conducted in Egypt. We evaluated the pathogenicity of ETEC isolates in a birth cohort of children living in a rural community in Egypt. Between 2004 and 2007, we enrolled and followed 348 children starting at birth until their second year of life. A stool sample and two rectal swabs were collected from children during twice-weekly visits when they presented with diarrhea and were collected every 2 weeks if no diarrhea was reported. From routine stool cultures, five E. coli-like colonies were screened for ETEC enterotoxins using a GM1 enzyme-linked immunosorbent assay (ELISA). The isolates were screened against a panel of 12 colonization factor antigens (CFAs) by a dot blot assay. A nested case-control study evaluated the association between initial or repeat excretion of ETEC and the occurrences of diarrhea. The pathogenicity of ETEC was estimated in symptomatic children compared to that in asymptomatic controls. ETEC was significantly associated with diarrhea (crude odds ratio, 1.37; 95% confidence interval [CI], 1.24 to 1.52). The distribution of ETEC enterotoxins varied between the symptomatic children (44.2% heat-labile toxin [LT], 38.5% heat-stable toxin [ST], and 17.3% LT/ST) and asymptomatic children (55.5% LT, 34.6% ST, and 9.9% LT/ST) (P < 0.001). The CFAs CFA/I (n = 61), CS3 (n = 8), CS1 plus CS3 (n = 24), CS2 plus CS3 (n = 18), CS6 (n = 45), CS5 plus CS6 (n = 11), CS7 (n = 25), and CS14 (n = 32) were frequently detected in symptomatic children, while CS6 (n = 66), CS12 (n = 51), CFA/I (n = 43), and CS14 (n = 20) were detected at higher frequencies among asymptomatic children. While all toxin phenotypes were associated with diarrheal disease after the initial exposure, only ST and LT/ST-expressing ETEC isolates (P < 0.0001) were associated with disease in repeat infections. The role of enterotoxins and pathogenicity during repeat ETEC infections appears to be variable and dependent on the coexpression of specific CFAs.
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| 3. |
- Shaheen, H I, et al.
(author)
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Phenotypic and genotypic analysis of enterotoxigenic Escherichia coli in samples obtained from Egyptian children presenting to referral hospitals.
- 2009
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In: Journal of clinical microbiology. - 1098-660X. ; 47:1, s. 189-97
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Journal article (peer-reviewed)abstract
- Hospital surveillance was established in the Nile River Delta to increase the understanding of the epidemiology of diarrheal disease among Egyptian children. Between September 2000 and August 2003, samples obtained from children less than 5 years of age who had diarrhea and who were seeking hospital care were cultured for enteric bacteria. Colonies from each culture with a morphology typical of that of Escherichia coli were tested for the heat-labile (LT) and heat-stable (ST) toxins by a GM-1-specific enzyme-linked immunosorbent assay and colonization factor (CF) antigens by an immunodot blot assay. Enterotoxigenic E. coli (ETEC) isolates were recovered from 320/1,540 (20.7%) children, and ETEC isolates expressing a known CF were identified in 151/320 (47%) samples. ST CFA/I, ST CS6, ST CS14, and LT and ST CS5 plus CS6 represented 75% of the CFs expressed by ETEC isolates expressing a detectable CF. Year-to-year variability in the proportion of ETEC isolates that expressed a detectable CF was observed (e.g., the proportion that expressed CFA/I ranged from 10% in year 1 to 21% in year 3); however, the relative proportions of ETEC isolates expressing a CF were similar over the reporting period. The proportion of CF-positive ETEC isolates was higher among isolates that expressed ST. ETEC isolates expressing CS6 were isolated significantly less often (P < 0.001) than isolates expressing CFA/I in children less than 1 year of age. Macrorestriction profiling of CFA/I-expressing ETEC isolates by using the restriction enzyme XbaI and pulsed-field gel electrophoresis demonstrated a wide genetic diversity among the isolates that did not directly correlate with the virulence of the pathogen. The genome plasticity demonstrated in the ETEC isolates collected in this work suggests an additional challenge to the development of a globally effective vaccine for ETEC.
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| 4. |
- Rockabrand, David M, et al.
(author)
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Enterotoxigenic Escherichia coli colonization factor types collected from 1997 to 2001 in US military personnel during operation Bright Star in northern Egypt.
- 2006
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In: Diagnostic microbiology and infectious disease. - : Elsevier BV. - 0732-8893. ; 55:1, s. 9-12
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Journal article (peer-reviewed)abstract
- Operation Bright Star (OBS) is a biennial, multinational exercise in Egypt involving 15000 US troops. Consistent with past observations in deployed troops, diarrhea is the most significant cause of morbidity. Focused efforts are ongoing to develop vaccines against the most common pathogens affecting our troops. As part of these efforts, diarrhea surveillance was conducted during OBS to monitor pathogens associated with illness and to identify new vaccine targets. A retrospective review was conducted of prior studies with similar methods. Soldiers with diarrhea presenting to the OBS clinic provided a stool sample that was inoculated into Carey-Blair transport media. Within 3 days, the Cary-Blair tubes were transported to the Naval Medical Research Unit no. 3 in Cairo where bacterial culture was performed. As part of the evaluation, 5 Escherichia coli-like colonies were collected and tested for toxin production using the GM1-ELISA. Toxin-positive isolates were further tested for colonization factors (CF) by a dot-blot assay using a standardized panel of monoclonal antibodies against CFA/I, CS1-CS7, CS17, CS8 (CFA/III), CS12 (PCFO159), and CS14 (PCFO166). Enterotoxigenic E. coli (ETEC) was the most frequently isolated pathogen during each OBS from which data were collected. The rate of ETEC-associated diarrhea ranged from 22% to 58%. Over time, there were dramatic shifts in the frequency and distribution of CFs. Over the 5 years of study, an increasing number of ETEC isolates had no known CF identified, and in 2001, only 40% of ETEC was associated with known CFs. The most commonly identified CF was CS6. Diarrheal disease, particularly ETEC, continues to be a common malady among US military personnel deployed to Egypt. We have identified ETEC CF types, especially CS6, which should be considered potential vaccine candidates. However, despite intensive testing, CFs could not be identified in most of the ETEC isolated, highlighting the need for further studies to identify novel CFs and alternative vaccine targets.
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| 5. |
- Rao, Malla, et al.
(author)
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Serologic correlates of protection against enterotoxigenic Escherichia coli diarrhea
- 2005
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In: J Infect Dis. ; 191:4, s. 562-70
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Journal article (peer-reviewed)abstract
- BACKGROUND: We conducted a nested case-control study in 397 rural Egyptian children <36 months of age to assess the correlation between serum levels of antibodies against toxin and colonization factors (CFs) and the risk of homologous enterotoxigenic Escherichia coli (ETEC) diarrhea. METHODS: Active case detection was performed via semiweekly home visits, and blood was obtained at 3-month intervals. After each serosurvey, case subjects were selected from children experiencing a CF antigen (CFA)/I-, CFA/II-, CFA/IV-, or heat-labile enterotoxin (LT)-ETEC diarrheal episode during the subsequent 3 months. Up to 5 control subjects per case subject were selected from children who did not experience an ETEC diarrheal episode during the corresponding interval. Serum titers of immunoglobulin G antibodies against CFA/I, coli surface antigen (CS) 3, CS6, and LT were measured by enzyme-linked immunosorbant assay. RESULTS: The distribution of serum titers of LT, CS3, and CS6 antibodies did not differ between the case and control subjects. For children <18 months of age, serum titers of CFA/I antibody were inversely related to the risk of CFA/I-ETEC diarrhea; reciprocal serum titers of CFA/I antibody > or =76 were associated with a 77% reduction in the odds of CFA/I-ETEC diarrhea. CONCLUSION: Induction of reciprocal serum titers of antibodies against CFA/I within or above the 76-186 range should be further evaluated as a predictor for assessment of the ability of candidate vaccines to protect against CFA/I-ETEC diarrhea.
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