Factors Determining the Colonization by Microbes
Factors that determine whether exposure to a microbe result in transient passage through a human host or prolonged colonization are complex and involve microbial properties, host characteristics, and environmental factors.
The most important factors that determine colonization in human body are the properties of the specific organism. For example, the oropharynx provides the organisms opportunities to colonize saliva, mucosal surface, tongue, and gingiva and teeth line. Thus oxygen-sensitive bacteria proliferate in the gingival crevices. Streptococcus mutans organisms adhere to the hard surface of teeth by polysaccharide. Bacteria can also bind to cells lining the oropharynx, intestine, and vagina via specific receptors for the bacterial pili. This type of adhesion prevents the mechanical elimination of organisms.
Various host factors determine the success of coloniza-tion with microbe. Nutritional and environmental conditions must favor the survival of microbes. The age of the host also influences microbial colonization. The hormonal secretions, alteration of dietary habits, person-to-person interaction, sexual activity, and many other factors determine the establish-ment of normal microbiota.