title: Enterotoxigenic Escherichia coli with STh and STp genotypes is associated with diarrhea both in children in areas of endemicity and in travelers.
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.
authors.affiliation: Department of Microbiology and Immunology, and Göteborg Vaccine Research Institute (GUVAX), Göteborg University, Göteborg, Sweden. ingrid.bolin@microbio.gu.se
authors.forename: Ingrid
authors.initials: I
authors.lastname: Bölin
authors.forename: Gudrun
authors.initials: G
authors.lastname: Wiklund
authors.forename: Firdausi
authors.initials: F
authors.lastname: Qadri
authors.forename: Olga
authors.initials: O
authors.lastname: Torres
authors.forename: A Louis
authors.initials: AL
authors.lastname: Bourgeois
authors.forename: Stephen
authors.initials: S
authors.lastname: Savarino
authors.forename: Ann-Mari
authors.initials: AM
authors.lastname: Svennerholm
mesh_terms: D000328:Adult; D001427:Bacterial Toxins / Q000235:genetics*; D002648:Child; D003967:Diarrhea / Q000382:microbiology*; D004768:Enterotoxins / Q000235:genetics*; D004926:Escherichia coli / Q000145:classification* / Q000472:pathogenicity; D029968:Escherichia coli Proteins; D005838:Genotype; D006801:Humans; D014195:Travel
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C034151:heat stable toxin (E coli)