Pathotypes of diarrheagenic Escherichia coli in children attending a tertiary care hospital in South India

Abstract

The prevalence of diarrheagenic Escherichia coli (DEC) in children under 5 years was studied in children with diarrhea and controls in South India. Four polymerase chain reaction (PCR) "schemes" were used to detect genes of the 6 pathotypes of DEC. In 394 children with diarrhea, 203 (52%) DEC infections were found. Among the 198 controls, 126 (63%) DEC infections were found. Enteroaggregative E. coli was the most common pathotype by multiplex PCR both in cases (58, 14.7%) and controls (47, 23.7%), followed by enteropathogenic E. coli seen in 10% cases and 8% of controls. Enterotoxigenic E. coli (ETEC), enterohemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC), and diffusely adherent E. coli (DAEC) were found in 4.1%, 2.0%, 1.0%, and 0.5% of cases, respectively. ETEC was found in 2.5% of controls, but EHEC, EIEC, and DAEC were not detected. Overall, no single assay worked well, but by discounting genes with a pathogenicity index of less than 1, it was possible to use the PCR assays to identify DEC in 75/394 (19%) cases and 12/198 (6.1%) controls, while mixed infection could be identified in 8/394 (2%) cases and 2/198 (1%) controls.

Fig. 1

(A) Multiplex PCR for DEC. Lane M: marker. Lane 1: EHEC—stx1 (348 bp), stx2 (584 bp), eae (482 bp). Lane 2: EPEC—eae (482 bp), bfp (300 bp). Lane 3: ETEC—lt (218 bp), stII (129 bp). Lane 4: EAEC—aafII (378 bp). Lane 5: DAEC—daaE (542 bp). Lane 6: EIEC—virf (618 bp), ipah (933 bp). Lane 7: ETEC—stI. (B) Multiplex PCR for EAEC. Lane M: marker. Lane 1: aap (310 bp). Lane 2: aap and aggR (457 bp). Lane 3: aap, aggR, and AA (629 bp).