Fimbrial haemagglutination by Neisseria gonorrhoeae.

The presence of filamentous appendages distinct from flagella was first discovered in electron microscope preparations by Anderson (1949) and Houwink and van Iterson (1950). Duguid, Smith, Dempster, and Edmunds (1955) confirmed the existence of these structures and suggested the name 'fimbriae' for them; others have called them 'cilia' (Pershina and Vasilieva, 1960) and 'pili' (Brinton, 1959). Because of the points Duguid and Anderson (1967) put forward in favour of the term 'fimbriae' it is perhaps the more correct form. Bacterial fimbriae are described as filamentous surface appendages having various diameters and lengths. They do not exhibit the sinuous forms characteristic of bacterial flagella, are devoid of any recognizable amplitude or wavelength, and are apparently not related to the motility of flagellated bacteria (Brinton, 1965; Duguid, Anderson, and Campbell, 1966); they can also be found in capsulated organisms, e.g. Klebsiella (Duguid, 1959). Fimbriae have been demonstrated in many of the enterobacteriaceae, and more recent studies have shown that other organisms also possess fimbriae, for example, Pseudomonas (Fuerst and Hayward, 1969); Vibrio (Tweedy, Park, and Hodgkiss, 1968); Herella (Swanson and Goldschneider, 1969) and Neisseria species (Wistreich and Baker, 1971; Jephcott, Reyn, and Birch-Andersen, 1971; Swanson, Kraus, and Gotschlich, 1971). Their occurrence is not limited to Gram-negative organisms, since they have been reported in various strains of streptococci (Swanson and McCarty, 1969) and Corynebacterium renale (Yanagawa and Otsuki, 1970). Fimbriae are usually thinner than flagella and may differ from them in detailed fine structure (Duguid and others, 1955; Brinton, 1967). Duguid (1959) suggested, on the basis of electron micrographs, that there may be two types of fimbriae, one with a diameter of 100nm. and the other 70nm.; he suggested that such a difference in apparent sizes might be a