What component of pathogenic microorganisms aids in adherence to host tissues?

Adhesins are specialized molecules found on the surface of pathogenic microorganisms that facilitate their adherence to host tissues. These structures can be proteins or glycoproteins that specifically bind to receptors on the host cells, making it more likely that the microorganism will successfully colonize and establish an infection. By adhering tightly to the host tissues, pathogens can resist being washed away by bodily fluids, such as saliva or mucus, and can also evade the host's immune responses.

While capsules can provide some level of protection and may indirectly assist in adherence by creating a sticky surface, they primarily serve as a means of evading the immune system rather than being specific adherence factors. Biofilms do allow groups of microorganisms to adhere to surfaces and can increase colonization success, but they are not a primary mechanism used by individual pathogens to stick to host cells. Flagella mainly assist in motility, allowing pathogens to move towards favorable environments, but do not directly facilitate adherence to tissues.