P pili, Type I pili, Curli pili, and Type IV pili
Uropathogenic strains of
Escherichia coli use both P pili and Type I pili to adhere to the urothelium of the urinary tract; without these pili, the bacteria would be physically removed by the flow of urine.
Some strains of
E. coli have curli pili, which, in addition to adhesion, provoke the host
inflammatory response.
Type IV pili confer twitching motility to some species, independent of flagella; Neisseria gonorrhoeae and Pseudomonas aeruginosa are examples of bacteria that "walk" via retraction of Type IV pili.
Gram-Positive bacteria
Also have pili-like structures; though assembled differently the pili of Gram-negative bacteria, they perform similar functions.
Spa, GAS M1, PI-1, PI-2
Spa pili, which are long and flexible, facilitate adherence of
Corynebacterium diphtheriae, the causative agent of diphtheria, to
epithelial cells of the pharynx.
Similarly, GAS M1 facilitates adherence of
Group A Streptococcus (aka, Streptococcus pyogenes) to pharyngeal epithelial cells.
PI-1 and PI-2 facilitate adherence of Group B Streptococcus (
Streptococcus agalactiae) to the cells of the lungs.
PI = Pilus Island, which refers to the gene loci. Group B streptococcus causes neonatal sepsis, pneumonia, and meningitis.
