logreduksjoner

Logreduksjoner, also known as log reductions, are used to quantify the decrease in viable microorganisms resulting from a decontamination, disinfection, or sterilization process. The reduction is expressed on a base-10 logarithmic scale: L = log10(N0/N), where N0 is the initial count of viable organisms and N is the count after treatment. A higher L indicates a greater reduction.

Example: If the initial population is 10^6 and 10^3 remain after treatment, the log reduction is 3, corresponding to a 99.9% reduction (1 − 10^−3).

Common references: 1-log (90%), 2-log (99%), 3-log (99.9%), 6-log (99.9999%).

Applications: Log reductions are used to quantify effectiveness of disinfection, sterilization, water treatment, food safety, and pharmaceutical or medical device sterilization processes.

Measurement and interpretation: Calculated from viable counts, and influenced by sampling variability, detection limits, and assay efficiency. If final counts fall below the assay detection limit, it is reported as at least a certain log reduction. Real-world reductions may be affected by matrices, organic matter, biofilms, and microbial clumping.

Other terms: The concept is related to decimal reduction and LRVs (log reduction values). It provides a concise metric to compare treatment efficacy across methods and scenarios.