Detection of diarrheagenic Escherichia coli by multiplex PCR

Diarrheagenic E.coli (DEC) are an important cause of childhood diarrhea.Identification of DEC strains needs to detect factors that determine the virulence of these organisms. There is not much data regarding the importance of DEC as a cause of diarrhea in children in India.The prevalence of DEC in children below five years with and without diarrhea was studied using two multiplex PCR assays.

Two multiplex polymerase chain reaction assays were used to detect genes of five types of DEC.The targets selected for each category were eae and bfpA (bundle-forming pilus) for Enteropathogenic E.coli (EPEC), hlyA for Enterohemorrhagic E.coli (EHEC), elt and stla for Enterotoxigenic E.coli (ETEC), CVD432 for Enteroaggregative E.coli (EAEC) and ial for Enteroinvasive E.coli (EIEC).

In 200 children with diarrhea 52 (26%) DEC infections were found. Among 100 controls 8 (8%) DEC infections were found. EAEC was the most common DEC by multiplex PCR both in cases (26, 13%)and controls (5,5%), followed by EPEC seen in 16% cases and 3% controls. ETEC and EIEC were found in 7 (3.5%) and 3 (1.5%) of the diarrheal cases. EIEC and ETEC were not detected in the control cases. EHEC was not isolated from either the diarrheal or control cases.

DEC strains are a significant cause of diarrhea in children. The two Multiplex PCR assays can be used for the detection of DEC in routine diagnostic laboratories. These assays are specific and sensitive for the rapid detection of DEC. EAEC was the most frequent pathotype in the population under study.