Three characteristics associated with enterotoxigenic Escherichia coli isolated from man

Abstract

In Dacca, Bangladesh, potent enterotoxin producing E. coli were isolated from many hospital cases of acute cholera like diarrhea. Enterotoxigenic (tox+) and non enterotoxigenic (tox-) isolates of E. coli were used to investigate possible means of differentiating tox+ E. coli from those (tox-) of the normal flora. The majority (81%) of the tox+ E. coli studied were found to be negative for sucrose fermentation, 85% exhibited retarded growth in a peptone medium at pH 8.5, and 92% released large amounts of ammonium sulfate precipitable materials into culture supernatant fluids; 66.6% exhibited all three of these properties. For the tox- group the respective values were found to be 50%, 31%, and 34%; only 9.3% exhibited all three properties. These results indicate that it may be possible to use phenotypic characteristics other than antigenic composition and enterotoxin production for the identification of enterotoxigenic E. coli.