An infection is defined as the active or passive invasion and subsequent propagation of pathogens in the body. These pathogens are either bacteria, viruses, fungi or parasites. They can trigger the endogenous defence system (immune system) and lead to the formation of specific antibodies or defence cells.
An infection is not to be confused with the population or colonisation of localized flora of the skin and mucous membrane. In an infection, the pathogen can be proven directly (for example: by growing bacteria, PCR) or through the immune reaction (for example: antibodies).
Conventional microbiological diagnostics
Molecular pathogen diagnostics