Enzyme-Linked Immunosorbent Assays for the Detection of Adhesion Factor Antigens of Enterotoxigenic Escherichia coli

Two hundred forty-four specimens of Escherichia coli isolated in Bangladesh and Thailand and identified as enterotoxin producers were tested for the presence of adhesion antigens by mannose-resistant hemagglutination, immunodiffusion, and enzyme-linked immunosorbent assays (ELISAs). Specific antisera to the antigens colonization factor antigen (CFA)/I, CFA/II (consisting of coli surface antigens [CS] 1, 2, and 3), and putative colonization factor antigen (PCF) 8775 (consisting of CS4, 5, and 6) were used in immunodiffusion tests and ELISAs. The results showed that the antigens could be detected in more strains by ELISA than by immunodiffusion. Twenty-nine percent of specimens of E. coli from Thailand and 47% from Bangladesh carried an adhesion antigen. Many of the strains had lost the ability to produce enterotoxins. Forty percent of strains from Thailand and 64% from Bangladesh that were still enterotoxigenic carried adhesion factors. These antigens were found on strains with heat-stable or heat-stable and heat-labile enterotoxin but not on strains producing only heat-labile enterotoxin. PCF8775 antigens were associated mainly with strains from Bangladesh, where 10 strains that produced only CS6 were detected.