Fimbriae

Short, slender, hair-like outgrowths made chiefly of the protein pilin, projecting from certain bacterial cells — mostly Gram-negative ones. They help bacteria stick to cells and surfaces and may serve as significant virulence factors; they are also called pili. Pathogenic E. coli and Salmonella use fimbrial adhesins to colonise the gut lining and food-contact surfaces, the first step in infection and biofilm formation. Vaccines and competitive-exclusion products sometimes target fimbrial antigens, and sanitisers must penetrate the biofilms that fimbriae help anchor to stainless steel.