Definitions

For biocides and disinfectants, terms such as “resistance”, “tolerance”, “decreased susceptibility”, “reduced susceptibility”, “insusceptibility” and “acquired reduced susceptibility” are used. On the basis of a recent proposal, isolates with increased MIC values compared to reference strains of the same species and isolates that are insufficiently killed by concentrations of a disinfectant solution below those for use (suspension tests or tests under practical conditions) are considered to be tolerant. Isolates are considered to be resistant if they are able to survive or multiply in a disinfectant solution, with or without direct evidence of infection as a result of the contamination, and if they are insufficiently killed by use concentrations of a disinfectant solution in suspension tests or in a test under practical conditions compared to culture collection strains of the same species or strains from efficacy standards (e.g. European norms). European standards exist among others for the determination of bactericidal, fungicidal and mycobactericidal activity. They also define minimum efficacy requirements using culture collection strains.