Serotyping and categorisation of Escherichia coli strains isolated between 1958 and 1992 from diarrhoeal diseases in Asia

A total of 3065 strains of Escherichia coli isolated between 1958 and 1992 from patients with diarrhoea in different countries were examined for virulence factors by hybridisation with biotinylated DIVA probes for genes that coded for production of heat-labile and heat-stable enterotoxins, enteroinvasiveness, production of verotoxins and attaching-and-effacing factor and were serotyped, Of the 3065 strains, 1998 were placed into one of four pathogenic categories by their virulence factors: 1057 enterotoxigenic E, coli (ETEC) comprising 30 O-groups, 73 serovars and 137 untypable strains; 132 enteroinvasive E, coli (EIEC) comprising 11 O-groups and 13 serovars; 64 verotoxin-producing E, coli (VTEC) comprising 11 O-groups, 17 serovars and 13 untypable strains; and 745 enteropathogenic E. coli (EPEC) comprising 34 O-groups, 92 serovars and 91 untypable strains, The remaining 1067 strains did not hybridise with any of the DNA probes used, About half the number of O-groups recognised were not restricted to a single pathogenic category, although the combinations of O- and H-antigens were different in each category.