Fimbriae, Bacterial

**Definition:** Thin, hairlike appendages, 1 to 20 microns in length and often occurring in large numbers, present on the cells of gram-negative bacteria, particularly Enterobacteriaceae and Neisseria. Unlike flagella, they do not possess motility, but being protein (pilin) in nature, they possess antigenic and hemagglutinating properties. They are of medical importance because some fimbriae mediate the attachment of bacteria to cells via adhesins (ADHESINS, BACTERIAL). Bacterial fimbriae refer to common pili, to be distinguished from the preferred use of pili, which is confined to sex pili (PILI, SEX).

**Tree numbers:** - A11.284.180.285 - A20.843

**Synonyms:** - Bacterial Fimbria - Fimbria, Bacterial - Bacterial Fimbriae - Common Fimbria - Common Fimbriae - Common Pilus - Common Pili - Pili, Common