A new genetic test for the rapid identification of shiga-toxines producing (STEC), enteropathogenic (EPEC) E. coli isolates from children.

Routine bacteriological techniques do not allow detection of the most frequent enteric pathogens in young children: enteropathogenic Escherichia coli (EPEC) and shigatoxinogenic E. coli (STEC/EHEC). Since there is no correlation between serotype and pathotype, a genotypic determination is therefore necessary for the identification of these pathogenic strains. We evaluated the Genotype EHEC test (Hain Life Science, Germany), a new rapid system based on DNA multiplex amplification and further hybridization for the detection of shigatoxin stx1, stx2 genes, intimin eae gene and invasin ipaH gene harbored by Shigella and enteroinvasive E. coli (EIEC). E. coli strains of various serogroups isolated from children with acute gastroenteritis, hemorrhagic colitis or hemolytic-uremic syndrome were tested. Their genotypes were first determined by standard in-house PCR. The strains collection included 11 STEC/EHEC (serogroups O157, O111, O26, O91, O-untypable) and nine EPEC (serogroups O26, O157, O55, O126, O127, O-untypable). The same strains were tested with Genotype EHEC. For all the strains, the hybridization banding pattern obtained by Genotype EHEC correlated with their expected genotypic characteristics. No specific equipment is required, except a thermocycler. Absence of electrophoresis system, of ethidium bromide staining and imaging system is a clear-cut advantage of Genotype EHEC. In addition, the short testing time (less than 2 h) optimizes treatment orientation. The Genotype EHEC test allows an easy and reliable identification of EHEC, STEC, EPEC and also EIEC. As such, it is a useful tool for the rapid diagnosis of diarrheal diseases.