By which mechanism do fimbriae or pill contribute to pathogenicity?

Many gram-negative bacteria possess rigid surface structures known as pill or fimbriae. They are smaller than flagella and consist of protein subunits called pilins. Ordinary pili playa role in the adherence of bacteria to host cells. Pili in streptococci, the M proteins, associate with lipotechoic acids to help the group A streptococci adhere to epithelial cells. Neisseria gonorrhoeae virulent strains possess pill, which assists these organisms to adhere to mucous membrane cells. Adherence to tissue cells inhibits phagocytic ability of white blood cells to a ceain degree, but capsules perform this function directly. Protein A of Staphylococcus au reus binds the Fc poion of IgG molecules and prevents complement attachment-activation. Flagella are organs of locomotion and allow bacterial movement toward or away from a chemotactic substance. Plasmids are circular DNA molecules that provide genes for antibiotic resistance.