Demonstration by immuno-electronmicroscopy of antigenic heterogeneity among P fimbriae of strains of Escherichia coli.

The identification of P fimbriae on urinary strains of Escherichia coli isolated from urine was made by observation of the patterns of mannose-resistant and eluting haemagglutination of erythrocytes of seven animal species (and including those of human p phenotype), and by haemagglutination-inhibition tests with hydatid-cyst fluid known to contain an analogue of P-fimbrial receptor. In tests with five different, pure P-fimbrial antisera prepared in rabbits, agglutinin titres of 37 P-fimbriate strains revealed differences in their reactivity; immuno-electronmicroscopy studies with the same five antisera showed that P-fimbriate strains were markedly different in the extent to which their P fimbriae were coated with antibody. The antigenic heterogeneity observed among P fimbriae is discussed with regard to the development of P-fimbrial vaccines.