Fimbriae and Haemagglutinating Activity in Strains of Proteus hauseri

SUMMARY: Fimbriae were seen with the electron microscope on each of 79 strains of Proteus hauseri when these were in the haemagglutinating phase, but were absent from the non-haemagglutinating phase. All strains were variably fimbriate. The fimbriate mutant became dominant under anaerobic or relatively anaerobic cultural conditions. The non-fimbriate mutant became dominant under aerobic conditions. The properties of Proteus fimbriae are compared with those of Escherichia coli and Shigella flexneri. The fimbriation change is correlated with other mutations in Proteus strains.