| 1. |
- Bölin, Ingrid, 1952, et al.
(författare)
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Enterotoxigenic Escherichia coli with STh and STp genotypes is associated with diarrhea both in children in areas of endemicity and in travelers.
- 2006
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Ingår i: Journal of clinical microbiology. - 0095-1137. ; 44:11, s. 3872-7
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Tidskriftsartikel (refereegranskat)abstract
- Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea among children in developing countries and in travelers to areas of ETEC endemicity. ETEC strains isolated from humans may produce a heat-labile enterotoxin (LT) and two types of the heat-stable enterotoxin STa, called STh and STp, encoded by the estA gene. Two commonly used assay methods for the detection of STa, the infant mouse assay or different enzyme-linked immunosorbent assays, are unable to distinguish between the two subtypes of ST. Different genotypic methods, such as DNA probes or PCR assays, may, however, allow such discrimination. Using gene probes, it has recently been reported that ETEC strains producing STp as the only enterotoxin are not associated with diarrhea. In this study, we have used highly specific PCR methods, including newly designed primers for STh together with previously described STp primers, to compare the relative distribution of STh and STp in ETEC isolated from children with diarrhea in three different geographically distinct areas, i.e., Bangladesh, Egypt, and Guatemala, and from travelers to Mexico and Guatemala. It was found that ETEC strains producing STp were as commonly isolated from cases of diarrhea as strains producing STh both in Egypt and Guatemala, whereas STp strains were considerably less common in Bangladesh. No difference was found in the relative distribution of STh and STp in ETEC strains isolated from travelers with diarrhea and from asymptomatic carriers. Irrespective of ST genotype, the disease symptoms were also similar in both children and travelers.
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| 2. |
- Gonzales, Lucia, et al.
(författare)
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Molecular Characterization of Enterotoxigenic Escherichia coli Isolates Recovered from Children with Diarrhea during a 4-Year Period (2007 to 2010) in Bolivia
- 2013
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 51:4, s. 1219-1225
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Tidskriftsartikel (refereegranskat)abstract
- Enterotoxigenic Escherichia coli (ETEC) is an important cause of childhood diarrhea. This study aimed to characterize ETEC strains isolated from Bolivian children aged <5 years according to enterotoxin profile, colonization factors (CFs), suggested virulence genes, and severity of disease. A total of 299 ETEC isolates recovered from children with diarrhea and 55 ETEC isolates from children without diarrhea (controls) were isolated over a period of 4 years. Strains expressing heat-labile toxin (LT) or heat-stable toxin (ST) alone were about equally common and twice as common as ETEC producing both toxins (20%). ETEC strains expressing human ST (STh) were more common in children aged <2 years, while ETEC strains expressing LT plus STh (LT/STh) were more frequent in 2- to 5-year-old children. Severity of disease was not related to the toxin profile of the strains. CF-positive isolates were more frequently identified in diarrheal samples than in control samples (P = 0.02). The most common CFs were CFA/I and CS14. CFA/I ETEC strains were more frequent in children aged <2 years than CS1+CS3 isolates and CS14 isolates, which were more prevalent in 2- to 5-year-old children. The presence of suggested ETEC virulence genes (clyA, eatA, tia, tibC, leoA, and east-1) was not associated with disease. However, east-1 was associated with LT/STh strains (P < 0.001), eatA with STh strains (P < 0.001), and tia with LT/STh strains (P < 0.001). A minor seasonal peak of ETEC infections was identified in May during the cold-dry season and coincided with the peak of rotavirus infections; this pattern is unusual for ETEC and may be important for vaccination strategies in Bolivia.
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| 3. |
- Mansour, A., et al.
(författare)
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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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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 52:7, s. 2595-2603
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Mansour, A., et al.
(författare)
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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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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 52:2, s. 587-591
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Nair, G Balakrish, et al.
(författare)
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Cholera due to altered El Tor strains of Vibrio cholerae O1 in Bangladesh.
- 2006
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Ingår i: Journal of clinical microbiology. - 0095-1137. ; 44:11, s. 4211-3
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Tidskriftsartikel (refereegranskat)abstract
- We determined the types of cholera toxin (CT) produced by a collection of 185 Vibrio cholerae O1 strains isolated in Bangladesh over the past 45 years. All of the El Tor strains of V. cholerae O1 isolated since 2001 produced CT of the classical biotype, while those isolated before 2001 produced CT of the El Tor biotype.
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| 6. |
- Sjöling, Åsa, 1968, et al.
(författare)
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Comparative analyses of phenotypic and genotypic methods for detection of enterotoxigenic Escherichia coli (ETEC) toxins and colonization factors
- 2007
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Ingår i: J Clin Microbiol. - 0095-1137. ; 45:10, s. 3295-3301
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Tidskriftsartikel (refereegranskat)abstract
- Enterotoxigenic Escherichia coli (ETEC) is one of the main causes of childhood-diarrhoea in developing countries and in travellers. However, this pathogen has often not been reported in surveys of diarrhoeal pathogens due to lack of simple standardized methods to detect ETEC in many laboratories. ETEC express one or both of two different enterotoxin subtypes; heat stable toxins (STh and STp), a heat labile toxin (LT) and more than 22 different colonisation factors (CFs) that mediate adherence to the intestinal cell wall. Here we compare established phenotypic and genotypic methods and newly developed PCR methods with respect to sensitivity, specificity, positive predictive value and ease of performance. The methods include GM1-ELISA and dot blot techniques using specific monoclonal antibodies (MAbs) for the phenotypic detection of the toxins and CFs, respectively as well as different PCR and DNA/DNA hybridisation techniques, including new PCR assays, for genotypic identification of the toxin and CF genes, respectively. We found very good general agreement in results derived from genotypic and phenotypic methods. In a few strains, LT and CFs were identified genetically but not phenotypically. Based on our analyses we recommend initial screening for ETEC in clinical samples by multiplex toxin gene PCR. Toxin positive strains may then be analysed by dot-blot tests for detection of the CFs expressed on the bacterial surface and by PCR for determination of additional CFs for which MAbs are currently lacking as well as for strains that harbour silent CF genes.
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