Analysis of P fimbriae on Escherichia coli O2, O4, and O6 strains by immunoprecipitation.

P fimbriae on Escherichia coli O2, O4, and O6 strains were analyzed by immunoprecipitation. Fimbrial extracts were prepared from a total of 35 strains and tested for precipitation with four anti-P-fimbria sera. The overall fimbrial composition of the strains was related to the O:K:H serotype, and two to three P fimbrial variants per strain were found on most of the O4 and some of the O6 strains. The O2 strains, in contrast, showed only one antigenic variant of P fimbriae per strain, which was serologically unrelated to those of the O4 and O6 strains. The results stress the multiplicity and serological complexity of E. coli P fimbriae.