Mannose-resistant haemagglutination and colonisation factors among Escherichia coli strains isolated from pigs

Ten heat-labile (LT) and 23 heat-stable (ST) enterotoxin-producing strains of enterotoxigenic Escherichia coli (ETEC) and 100 non-enterotoxigenic E coli (non-ETEC) strains isolated from pigs with diarrhoea were examined for the presence of colonisation factors by means of mannose-resistant haemagglutination and serological tests. Seven of 10 LT strains, one of 23 ST and 18 of 100 non-ETEC carried K88 antigen; and four ST and four non-ETEC strains possessed CFA/I antigen. All strains carrying K88, K99 and CFA/I antigens were positive in the mannose-resistant microhaemagglutination (MRMH) test but four ST and 14 non-ETEC isolates positive in the MRMH test did not possess K88, K99 or CFA/I antigens. A considerable number of non-ETEC strains were positive in the MRMH test but lacked K88 and K99 antigens, suggesting that other unknown haemagglutinating colonisation factors may exist in porcine E coli strains.