Escherichia colidiarrhoea

Ever since Escherich (1885) first isolated the organism now known as Escherichia coli from the stools of infants, medical microbiologists have been faced with the problem of distinguishing between those strains capable of causing diarrhoea and those that are harmless gut commensals. Epidemiological investigations were greatly facilitated by the description by Kauffmann (1947) of a serotyping scheme for E. coli , and Taylor (1961) later reported that 17 0 serogroups of E. coli had been implicated as possible causes of epidemic infantile enteritis. These infantile enteropathogenic E. coli (EPEC), having been discovered by epidemiological studies using serotyping, belonged by definition to a restricted range of serogroups. More recently it was shown that other E. coli strains may produce enterotoxins, and these enterotoxigenic E. coli (ETEC) usually belong to particular serogroups which are different from those associated with EPEC. E. coli strains belonging to a third range of serogroups may cause an illness resembling shigella dysentery, and these may be regarded as entero-invasive E. coli (EIEC). E. coli strains that cause diarrhoea may therefore be considered as three groups, as follows.