Test for Escherichia coli Enterotoxin Using Infant Mice: Application in a Study of Diarrhea in Children in Honolulu

Abstract

In a new test for detection of Escherichia coli enterotoxin, supernates of broth cultures were injected into the stomachs of infant mice and fluid accumulation in the intestine was measured after 4 hr by weighing. Results with known positive and negative strains were comparable to those obtained with the rabbit-loop test, and the mouse test was easier to perform. Cholera toxin, unlike E. coli enterotoxin, did not dilate infant mouse intestine significantly, even in high concentrations. Use of the infant-mouse test in a study of 37 children with diarrhea in Honolulu revealed no enterotoxin-producing coliform bacteria in the stools. This is in contrast to studies reported from India, where such strains were found in a large proportion of undifferentiated cases of acute diarrhea in adults. None of 15 stock strains of E. coli serotypes generally thought to be enteropathogenic produced significant amounts of enterotoxin as measured by the test in mice.