Resistance of gnotobiotic large white and Chinese piglets to in vivo attachment of a K88ab enterotoxigenic Escherichia coli strain.

In vivo adhesion of a K88ab-positive enterotoxigenic Escherichia coli (ETEC) strain to the small intestinal wall of gnotobiotic, colostrum-deprived Chinese and Large White piglets was investigated. A non-enterotoxigenic, attachment factor-deprived E. coli strain, inoculated in association with the K88ab ETEC strain, was used as a marker to determine the content residues on the intestinal walls of gnotobiotic piglets. Both strains were selectively numerated in the luminal contents and on the washed wall from three segments of the small intestine. In vivo attachment was assessed by the ratio between the number of K88ab ETEC adherent to the wall and the number of both the E. coli strains which came from the luminal content residues and were not completely removed by washing. This ratio was first calculated in one group of 8 Large White piglets associated with the marker strain and with a K88ab antigen-deprived E. coli which derived from the parental K88ab ETEC strain. Thus, the range of the ratio was determined in those piglets where no attachment was expected. A comparison between the latter values of the ratio and the values obtained from 15 Large White and 10 Chinese piglets inoculated with the marker strain and the K88ab ETEC strain allowed us to classify the Large White piglets into adhesive (8 piglets) and non-adhesive (7 piglets) phenotypes and to show that the 10 Chinese piglets belonged to the non-adhesive phenotype.