Clonal groups of enteropathogenic Escherichia coli isolated in case-control studies of diarrhoea in Bangladesh

Recent case-control studies in Bangladesh showed a high prevalence of enter opathogenic Escherichia coli (EPEC) strains (identified by DNA probes for v irulence genes) associated with childhood diarrhoea, However, the clonal st atus of these strains is not known. A total of 94 EPEC isolates from 80 chi ldren with diarrhoea and 14 healthy matched controls isolated during 1991-1 992 and 1993-1994 was characterised by serogrouping, enterobacterial repeti tive intergenic consensus sequence PCR, and by a biochemical fingerprinting method (the phene plate or PhP system). Twelve O serogroups were found wit h O114 (n=19) and O127 (n = 23) being the dominant serogroups, Most strains of O114 belonged to the same PhP/PCR types. Strains of O127 contained 16 t hat produced cytolethal distending toxin (CDT) and seven that did not; both were found among patients as well as controls. Results of PCR and PhP typi ng showed that CDT-positive strains belonged to the same clonal group and w ere related to one of the two PhP/PCR types of CDT-negative O127 strains. T hirty-one EPEC strains were O non-typable and 21 strains belonged to other less prevalent serogroups, These strains belonged to diverse PhP/PCR types and did not show any similarity to the strains of two major serogroups, O11 4 and O127, The results suggest that two clonal groups of EPEC strains are predominantly associated with childhood diarrhoea in Bangladesh.