But a small number of the vast array of microbes in the environment are able to colonize or infect humans. The characteristics that allow them to do this are defined as virulence factors. It is important to identify and understand the action of virulence factors responsible for selective microbial pathogenicity, since an ideal method of prevention, or possibly treatment, of infection involves neutralizing virulence factors, eg, the development of an antitoxin or treatments that will prevent a pathogen from colonizing the host.
Traditional wisdom holds that preferential growth characteristics in the various environmental niches on the skin or mucous membranes determine the flora. However, the potent cleansing forces of dilution, wash out, or desquamation on the host surfaces probably prevent most organisms from colonizing humans unless a mechanism exists that enables the organisms to stick. Persistent colonization must involve a balance among attachment, growth, desorption,
Feingold DS. Bacterial Adherence, Colonization, and Pathogenicity. Arch Dermatol. 1986;122(2):161-163. doi:10.1001/archderm.1986.01660140051015