title: Use of a hemadsorption technique to evaluate the stability of the hemagglutination reaction of Escherichia coli cultures possessing human colonization factor antigens.
abstract: Two strains of Escherichia coli, producing different colonization factor antigens (CFA), were monitored for the population density of CFA-producing bacteria after repeated subculture. The production of CFA was estimated by flooding agar plates containing isolated colonies with suspensions of human or bovine erythrocytes. The erythrocytes were suspended in a low-ionic-strength buffer and were fixed to CFA-positive colonies with a 1.0% tannic acid solution. Strain H-10407, possessing CFA/I fimbriae, showed a rapid loss of the hemagglutinin when subcultured, whereas strain CL-9699, producing CFA/II, was very stable. By using the hemadsorption assay, we could rapidly and easily distinguish CFA- positive colonies from the CFA-negative variants. A survey of additional E. coli strains demonstrated the utility and specificity of the hemadsorption technique used.
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis*; D002417:Cattle / Q000097:blood; D004926:Escherichia coli / Q000145:classification / Q000276:immunology*; D036781:Fimbriae Proteins; D006382:Hemadsorption; D006384:Hemagglutination; D006801:Humans
chemical_list: D000942:Antigens, Bacterial; C022924:colonization factor antigens; D036781:Fimbriae Proteins