The skin and mucous membranes of healthy individuals maintain normal functions with naturally occurring microorganisms on them. The numbers and types of these microorganisms depend on moisture level, pH, nutrient availability, the presence or absence of inhibitory materials and the immunological tolerance of different sites of the body. Microorganisms generally found on skin, on mucous membranes and in the gastrointestinal (GI) tract of healthy individuals constitute the normal microflora, meaning they are normally present and do not cause problems in healthy individuals. People would have continual microbial infections—boils, abscesses, inflammation, diarrhea and intestinal gas/bloating—if they did not live in harmony with their normal microflora.
