U.S. Department of Defense


Date of this Version



The Journal of Infectious Diseases (1986), 154(2), p. 338-341


Escherichia coli is one of several agents that cause intestinal disease in humans and animals. Four classes of E. coli have been recognized [1], Enterotoxigenic E. coli (ETEC) strains produce a heat-labile (LT) enterotoxin and/or a heat-stable( ST) enterotoxin. Enteroinvasive E . coli (EIEC) strains, like shigellae, penetrate and multiply within epithelial cells. Enteropathogenic E. coli (EPEC) strains belong to certain serogroups that have been incriminated as pathogens by epidemiological studies. Some EPEC strains have been shown to adhere to cells of the intestinal mucosa and to produce pathognomonic lesions at the site of attachment. Enterohemorrhagic E. coli (EHEC) strains cause a distinct clinical syndrome (hemorrhagic colitis), and serotype 0157:H7 has been associated with this illness. Neither EPEC nor EHEC strains produce classic enterotoxins, nor are they enteroinvasive.

Some strains of E. coli produce a cell-associated cytotoxin that is neutralized by antibodies against purified Shiga toxin from Shigella dysenteriae type 1 [2-4]. The cytotoxins purified from one EPEC strain 026:H11 (H30) and from one EHEC strain 0157:H7 (933) have biologic activities (cytotoxicity for HeLa and Vero cells, lethality for mice, and enterotoxicity for ligated ileal segments from rabbits) and subunit structures similar to those of Shiga toxin [5, 6]. The purpose of this study was to determine the frequency and levels of cytotoxin production for a wide variety of E. coli strains. Culture supernatants and sonic lysates of 418 strains isolated from humans, animals, and food were examined for cytotoxic effects on HeLa cells and to see whether cytotoxicity could be neutralized by antibodies to Shiga toxin.