A study of Escherichia coli strains isolated from pigs with gastro-intestinal disease.

When 200 Escherichia coli isolated from pigs with gastro-intestinal disease were examined, 82.0% of them were found to be enteropathogenic by the ligated intestine test in pigs. Among the 18.0% which were nonenteropathogenic, 12.0% were obtained from pigs considered likely to be suffering from colibacillosis and 6.0% were from pigs for which there was a satisfactory diagnosis. Eighty-seven percent of the enteropathogens belonged to the serogroups O8:K87;88ac, O116:K"V17";88ac, O147:K89;88ac, O138:K81 and O45:K"E65";88ac. One O4 isolate and two O98 isolates were enteropathogenic, although members of these O groups have not been recognized enteropathogenic types. The majority (153) of the enteropathogens were of the types which are well characterized and which induce fluid accumulation in ligated segments of the intestine of young and old pigs and were referred to as class 1 enteropathogens. A small number (11)were able to cause fluid accumulation in ligated segments of young, but not of older pigs and were referred to as class 2 enteropathogens. Enterotoxin production was demonstrated for strains of all the serogroups of class 1 enteropathogens detected, and transfer of the enterotoxin plasmid was carried out for strains of O groups 4, 45, 98, 116 and 147.