Fimbriae
Attachment of bacteria to host surfaces is required for colonization during infection or to initiate formation of a biofilm. A fimbria is a short pilus that is used to attach the bacterium to a surface. Fimbriae are either located at the poles of a cell, or are evenly spread over its entire surface. Mutant bacteria that lack fimbriae cannot adhere to their usual target surfaces and, thus, cannot cause diseases.
Some fimbriae can contain lectins. The lectins are necessary to adhere to target cells because they can recognize oligosaccharide units on the surface of these target cells. Other fimbriae bind to components of the extracellular matrix.
Fimbriae are found in both Gram-negative and Gram-positive bacteria. In Gram-positive bacteria, the pilin subunits are covalently linked.
Read more about this topic: Pilus