Production of enterotoxin by Escherichia coli at four, twenty-two and thirty-seven degrees centigrade.

One hundred and seventy-seven Escherichia coli strains isolated from food, pigs and humans were tested for the production of heat-labile and heat-stable enterotoxin at 4, 22, and 37 degrees C. Heat-labile enterotoxin was detected in culture supernatants by an enzyme-linked immunosorbent assay, and heat-stable enterotoxin by the infant mouse bioassay. Thirty strains produced heat-labile enterotoxin, and twenty heat-stable enterotoxin. None of the strains isolated from food were enterotoxigenic. Fifty-seven per cent of the human and porcine strains producing heat-labile enterotoxin at 37 degrees C also produced the toxin at 4 degrees C. The fact that Escherichia coli enterotoxin may be present in food at consumption must be considered pathogenetically relevant.