Enterotoxigenic Escherichia coli and Other Gram-Negative Bacteria of Infantile Diarrhea: Surface Antigens, Hemagglutinins, Colonization Factor Antigen, and Loss of Enterotoxigenicity

Heat-labile enterotoxin (LT)-producing Escherichia coli and other enteric bacteria isolated from diarrheal Ethiopian children were studied for 0 and K antigen, production of heat-stable enterotoxin (ST), stability of LT production, properties of mannoseresistant hemagglutination (MRHA) (indicative of adhesive properties), and colonization factor antigen (CFA). Of the E. coli strains, 33% possessed 06, 08, or 078; 93% of these were stable producers of LT, and 86070 produced both LT and ST. 078 strains possessed CFA/I, whereas 06 and 08 strains possessed CFA/II. The E. coli with 0 antigens other than 06, 08, or 078, as well as the non-E. coli bacteria tended to lose their ability to produce LT; only 16070 produced ST, and they only occasionally showed MRHA properties. The former group of E. coli strains might be considered as true enteropathogenic bacteria (enterovirulent E. coli), which may be identified serologically, while the pathogenic significance of the diversified latter group remains less certain.