title: Molecular characterization of enterotoxigenic Escherichia coli isolates recovered from children with diarrhea during a 4-year period (2007 to 2010) in Bolivia.
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.
authors: Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.
authors: Lucia
authors: L
authors: Gonzales
authors: Samanta
authors: S
authors: Sanchez
authors: Silvia
authors: S
authors: Zambrana
authors: Volga
authors: V
authors: Iñiguez
authors: Gudrun
authors: G
authors: Wiklund
authors: Ann-Mari
authors: AM
authors: Svennerholm
authors: Asa
authors: A
authors: Sjöling
mesh_terms: D001427:Bacterial Toxins / Q000235:genetics; D001838:Bolivia / Q000453:epidemiology; D002675:Child, Preschool; D003967:Diarrhea / Q000453:epidemiology* / Q000382:microbiology* / Q000473:pathology; D054307:Enterotoxigenic Escherichia coli / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology* / Q000473:pathology; D029968:Escherichia coli Proteins / Q000235:genetics; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D017720:Molecular Epidemiology; D012621:Seasons; D037521:Virulence Factors / Q000235:genetics
chemical_list: D001427:Bacterial Toxins; D029968:Escherichia coli Proteins; D037521:Virulence Factors
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