Terminology of Bacterial Fimbriae, or Pili, and their Types

THE nomenclature of the non-flagellar filamentous appendages of bacteria is in a confused state and the need for clarification is increased by a renewal of interest brought about by findings that suggest that some types of these structures may play a part in bacterial conjugation 1–4 . The appendages were first clearly described and distinguished from flagella and extracellular slime by Houwink and van Iterson 5 , who called them “filaments”, an unspecific term which was also used by Brinton et al. 6 . The distinctive name, “fimbriae”, was proposed by Duguid et al. 7 in 1955 and has since been adopted by most authors publishing work on the subject in Britain and elsewhere.