[Demonstration of strains of Escherichia coli with septicemic characteristics in the feces of calves with mucoid enteritis].

During a field study on neonatal diarrhea of calves, we examined the bacteremic ability of 78 strains of Escherichia coli isolated from diarrheic and non-diarrheic newborn calves. The following tests were performed: growth in newborn calf serum, mortality in adult mice inoculated intraperitoneally with about 5 X 10(7) bacteria, mortality and effect on weight gain in baby mice inoculated by oral route with about 10(8) bacteria. In addition, we tested their ability to adhere in vitro to intestinal villi of newborn lamb. Among the 78 isolates, 58% were able to grow in newborn calf serum and 22% were non-adherent to lamb intestinal villi. Fifteen isolates were pathogenic for adult mice, 12 of them originating from calves with a syndrome that we called "mucoid enteritis" and which consisted of the following signs: very abundant feces, bright and viscous, containing mucus, and physical prostration. From the 15 strains displaying a lethal effect on adult mice, 12 were adherent and 7 provoked at least 20% mortality in baby mice. Our observations suggest that bacteriemic E. coli with adhesive properties could be responsible for mucoid enteritis in calves.