An outbreak of gastroenteritis due to a heat-labile enterotoxin-producing strain of Escherichia coli.

In April 1981, an outbreak of gastroenteritis, characterized by diarrhea and abdominal cramps, occurred in 282 of approximately 3,000 personnel at a large metropolitan hospital in San Antonio, Tex. There was a significant association between illness and eating at the hospital cafeteria (P = 0.0008), but no specific food could be incriminated. Stools or rectal swabs from 54 ill individuals produced almost pure cultures of Escherichia coli. Cultures from 51 of these subjects had identical antibiotic sensitivity patterns, and 38 had the same biotype. Isolates from 45 persons were tested for production of heat-stable and heat-labile enterotoxins, using the suckling mouse and Y-1 adrenal cell assays, respectively. Of 45 isolates, 41 produced heat-labile enterotoxins, while 0 of 45 produced heat-stabile enterotoxins. Two isolates were rough, and 34 of the remaining 43 were serotype O25:H-. Two strains were O25:H+. None of the 45 strains possessed hemagglutination patterns typical of colonization factor antigens I or II. Six of seven O25:H- heat-labile enterotoxin-positive strains selected at random were piliated as seen by electron microscopy but did not agglutinate with anti-colonization factor antigens I or II antisera.