Serotype-related enterotoxigenicity inEscherichia coliO6.H16 and O148.H28

Abstract

SUMMARY: The ability of certainEscherichia colistrains to produce enterotoxin is determined by transmissible plasmids. It is therefore possible that anyE. colistrain might be able to acquire such a plasmid and that the correlation between enterotoxigenicity and serotype might be random. However, recent studies show that the enterotoxigenic strains so far described belong to a restricted range of serotypes. Enterotoxigenic strains ofE. coliO6.H16 andE. coliO148.H28 have been associated with outbreaks of diarrhoea in several countries, therefore strains ofE. colibelonging to these serotypes were selected for further study.Twenty-three strains ofE. coliO6.H16 and 14 strains ofE. coliO148.H28 were examined; 20 strains ofE. coliO6.H16 and all 14 strains ofE. coli0148.H28 were enterotoxigenic but strains ofE. coliO6 with flagellar antigens other than H16 and strains ofE. coliO148 with flagellar antigens other than H28 were not enterotoxigenic. The examination of single colony subcultures derived from theE. coliO6.H16 strains showed that in some strains loss of enterotoxigenicity had occurred in a proportion of colonies.