Attaching and Effacing Bacteria in the Intestines of Calves and Cats with Diarrhea

Histopathologic and electron microscopic examination of intestines of three calves and two cats revealed attaching effacing bacteria characteristic of enteropathogenic Escherichia coli (EPEC) in ileum, cecum, and colon. The attaching effacing bacteria in one of the calves contained bacteriophages, and an E. coli isolate from that calf was shown to produce Shiga-like toxin. These findings contribute to emerging evidence that attaching effacing intestinal bacteria are globally distributed pathogens in a variety of host species and that bacteriophage-mediated production of Shiga-like toxin is related to the virulence of such bacteria. There are at least three different mechanisms by which Escherichia coli cause (1) Entero- toxigenic E. coli (ETEC) adhere to the surfaces of in- testinal epithelial cells and produce classical heat-labile (LT) and heat-stable (ST) enterotoxins which cause intestinal secretion and cholera-like disease; (2) En- teroinvasive E. coli (EIEC) invade, multiply in, and destroy intestinal epithelial cells causing a disease sim- ilar to bacillary dysentery (shigellosis); (3) The term enteropathogenic E. coli (EPEC) has been used to des- ignate E. coli strains that do not produce classical enterotoxins and are not enteroinvasive, but cause in- testinal infection and diarrhea by unknown mech- anisms. Some EPEC strains isolated from humans,17,23,27 rab- bit~,'~ and calves4 attach intimately to the surfaces of intestinal epithelial cells and efface microvilli from them, resulting in characteristic histologic and ultra- structural lesions. The term attaching effacing E. coli (AEEC) has been used to designate EPEC that cause these characteristic lesions. 'I The effacing activity of AEEC is thought to be caused by a cytotoxin (Shiga- like toxin) delivered to the epithelium by the intimately attached bacteria. 15.24 Calf diarrhea associated with AEEC infections has been reported in the United States8J2 and Great Britain.4 We report here that le- sions characteristic of those produced by AEEC oc- curred in diarrheal cats and calves in West Germany.