Target cell specificity of wild-type E. coli and mutants and clones with genetically defined adhesins

The species, individual and tissue specificity of bacterial binding reactions was studied using wild-type E. coli strains from diarrhoea or urinary tract infection, and derivatives with genetically manipulated adhesins. E. coli J96 and GR12 were isolated from the urine of patients with acute pyelonephritis; E. coli strains expressing the CFAI and II antigens from the stools of patients with diarrhoea. E. coli J96, GR12 and CFAI induced mannose-resistant agglutination of human erythrocytes; E. coli J96 and GR12 in addition carried mannose-sensitive adhesins. Mutants of GR12 with either or both of these adhesins were obtained through chemical mutagenesis. Cloning of 6-8 mdal fragments of chromosomal DNA from J96 into E. coli K12 resulted in expression of pili and binding properties in the previously non-piliated and non-binding strain. Bacterial binding was registered to target cells from different human tissues; small intestinal brush borders, uroepithelial and buccal cells and erythrocytes and was compared between species using rabbit intestinal brush borders, mouse bladder cells and guinea pig erythrocytes. Individual variation was illustrated by agglutination of human P1 erythrocytes and those of blood group p lacking the globoseries glycolipid receptors. Specific recognition of globoseries glycolipid receptors was defined as capacity to agglutinate guinea pig erythrocytes after but not before coating with globotetraosylceramide. Binding specific for mannose-containing receptors was diagnosed by mannose-reversible agglutination of guinea pig erythrocytes. The binding pattern of the wild-type strains was related to the site of infection, i.e. the CFAI and II strains bound to small intestinal brush borders and the pyelonephritogenic E. coli to uroepithelial cells, but not vice versa. The mutants and clones retained the binding properties of the parent/donor both in degree and specificity of binding. Strains with adhesins specific for globoseries glycolipids attached to human uroepithelia, mouse uroepithelial and buccal cells. Within the group of strains with mannose-sensitive adhesins heterogeneity was observed. Strains sharing ability to agglutinate guinea pig erythrocytes to a mannose-reversible manner bound or did not bind to human buccal cells, to human uroepithelial cells and agglutinated or did not agglutinate human erythrocytes. The results demonstrate the usefulness of genetic technology in the study of bacterial binding reactions. The role of pili as adhesins is discussed.