Ruggedness and reproducibility of the MBEC biofilm disinfectant efficacy test

article i nfo Article history: The MBEC™ Physiology & Genetics Assay recently became the first approved ASTM standardized biofilm disinfec- tant efficacy test method. This report summarizes the results of the standardization process using Pseudomonas aeruginosa biofilms. Initial ruggedness testing of the MBEC method s uggests that the assay is rugged (i.e., insensi- tive) to small changes to the protocol with respect to 4 factors: incubation time of the bacteria (when varied from 16 to 18 h), treatment temperature (20-24 °C), sonication duration (25-35 min), and sonication power (130-480 W). In order to assess the repeatability of MBEC results across multiple tests in the same laboratory and the reproducibility across multiple labs, an 8-lab study was conducted in which 8 concentrations of each of 3 disinfectants (a non-chlorine oxidizer, a phenolic, and a quaternary ammonium compound) were applied to biofilms using the MBEC method. The repeatability and reproducibility of the untreated control biofilms were acceptable, as indicated by small repeatability and reproducibility standard deviations (SD) (0.33 and 0.67