Enterobacterial fimbriae.

Many different species of the family Enterobacteriaceae have been shown to possess fimbrial appendages which emerge from the bacterial cell as straight, rigid organelles distinct from flagella (14). The role of fimbriae (synonym: pili) as adhesins in both enterotoxigenic and uropathogenic isolates of Escherichia coli has been demnonstrated, and thus the identification of such appendages as virulence determinants was established. Enterotoxigenic E. coli strains possess a number of distinct antigenic types of fimbriae facilitating attachment to the epithelial cells of the gastrointestinal tract, and these have been reviewed in detail elsewhere (18). Similarly, the fimbrial adhesins of urinary isolates of E. coli and the role of these fimbriae ir facilitating colonization of uroepithelial cells have been the subject of extensive investigation (25, 32). Consequently, this review concentrates on recent developments as they pertain to fimbriae of members of the Enterobacteriaceae other than E. coli, and E. coli antigens will be considered only in comparison with heterologous fimbriae.