Type-I fimbriae enable E. coli to bind to D-mannose residues on eucaryotic cell surfaces. Type-I fimbriae are said to be "mannose-sensitive" since exogenous mannose blocks binding to receptors on red blood cells. Although the primary 17kDa fimbrial subunit is the major protein component of Type-1 fimbriae, the mannose-binding site is not located here, but resides in a minor protein (28-31kDa) located at the tips or inserted along the length of the fimbriae. By genetically varying the minor "tip protein" adhesin, the organisms can gain ability to adhere to different receptors. For example, tip proteins on pyelonephritis-associated (pap) pili recognize a galactose-galactose disaccharide, while tip proteins on S-fimbriae recognize sialic acid.

Pseudomonas, Vibrio and Neisseria possess Type IV pili that contain protein subunit with a methylated amino acid, often phenylalanine, at or near its amino terminus. These "N-methylphenylalanine pili" have been established as virulence determinants in pathogenesis of Pseudomonas aeruginosa lung infection in cystic fibrosis patients. These type of fimbriae occur in Neisseria gonorrhoeae and their receptor is thought to be an oligosaccharide. Type IV pili are the tcp (toxin coregulated pili) fimbriae used in attachment of Vibrio cholerae to the gastrointestinal epithelium.

The adhesins of Streptococcus pyogenes are controversial.  In 1972, Gibbons and his colleagues demonstrated that attachment of streptococci to the oral mucosa of mice is dependent on M protein. Olfek and Beachey argued that lipoteichoic acid (LTA), rather than M protein, was responsible for streptococcal adherence to buccal epithelial cells. In 1996, Hasty and Courtney proposed a two-step model of attachment that involved both M protein and teichoic acids.  They suggested that LTA loosely tethers streptococci to epithelial cells, and then M protein secures a firmer, irreversible association. In 1992, protein F was discovered and found to be a fibronectin binding protein. More recently, in 1998, M proteins M1 and M3 were also found to bind to fibronectin. Apparently, S. pyogenes produces multiple adhesins with varied specificities.

Electron micrograph of Streptococcus pyogenes (Group A strep) by Maria Fazio and Vincent A. Fischetti, Ph.D. with permission. The Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University. The cell surface fibrils, that consist primarily of M protein, are clearly evident.  The M protein has several possible roles in virulence: it is involved in adherence, resistance to phagocytosis, and in antigenic variation of the pathogen.

Staphylococcus aureus also binds to the amino terminus of fibronectin by means of a fibronectin-binding protein which occurs on the bacterial surface. Apparently S. aureus and Group A streptococci use different mechanisms but adhere to the same receptor on epithelial surfaces.

Treponema pallidum has three related surface adhesins (P1, P2 and P3) which bind to a four-amino acid sequence (Arg-Gly-Asp-Ser) of the cell-binding domain of fibronectin. It is not clear if T. pallidum uses fibronectin to attach to host surfaces or coats itself with fibronectin to avoid host defenses (phagocytes and immune responses).