Microorganisms are present almost everywhere in our environment. If one counts the cells of our body and puts this number in relation to the number of microorganisms living on the skin and in the digestive tract, one finds that only 10 % of our body is human. The remaining 90 % are our microbiome. Almost every day, these micro-organisms give us faithful service in food intake and protection of our skin or in numerous industrial applications such as food production or biotechnology.

However, this contact is particularly critical in the case of direct exposure of the immune system, for example in medical applications (parenteral application, medical implants, dialysis or surgery) or in chronic exposure to the working environment (dermal or inhalation). Because of this particularly high sensitivity in medical applications release tests for sterility are prescribed in Chapter EP 2.6.1 (Sterility) and more specifically for cell based preparations in EP 2.6.27.