Ruggedness and reproducibility of the MBEC biofilm disinfectant efficacy test

Abstract

The MBEC™ Physiology & Genetics Assay recently became the first approved ASTM standardized biofilm disinfectant efficacy test method. This report summarizes the results of the standardization process using Pseudomonas aeruginosa biofilms. Initial ruggedness testing of the MBEC method suggests that the assay is rugged (i.e., insensitive) to small changes to the protocol with respect to 4 factors: incubation time of the bacteria (when varied from 16 to 18h), treatment temperature (20-24°C), sonication duration (25-35min), and sonication power (130-480W). 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 log10(CFU/mm(2)), respectively). The repeatability SDs of the biofilm log reductions after application of the 24 concentration and disinfectant combinations ranged from 0.22 to 1.61, and the reproducibility SDs ranged from 0.27 to 1.70. In addition, for each of the 3 disinfectant types considered, the assay was statistically significantly responsive to the increasing treatment concentrations.

Rifamycin Derivatives Are Effective Against Staphylococcal Biofilms In Vitro and Elutable From PMMA

“…However, the biofilm model used in this study is well characterized and has been demonstrated to be a reliable, reproducible experimental tool for evaluating susceptibilities of bacterial biofilms to various agents [3,11,13]. Importantly, the ruggedness (ie, insensitivity) of the assay to small changes in the protocol [46] allows investigators to use these models to evaluate treatments independent of laboratory conditions, making it a useful model for susceptibility testing.…”

Targeted antibiotic delivery using low temperature-sensitive liposomes and magnetic resonance-guided high-intensity focused ultrasound hyperthermia

“…The efficacy of LTSL against biofilms was determined using a well-established MBEC 96-well plate system (Innovotech, Edmonton, Alberta, Canada) that allows for high throughput screening of test agents [30]. Briefly, MBEC wells were filled with 150 μL of S. aureus culture (1.0 × 10 7 CFU mL −1 ), and then were incubated for 5 days in a humidified gyro-rotary shaker rotating at 150 rpm at 37 °C to establish a biofilm on the pegs located on the lid of the device.…”

Measuring Antimicrobial Efficacy against Biofilms: a Meta-analysis

“…The mature biofilm is then exposed simultaneously to multiple concentrations of biocide by placing the lid on a new microtiter plate bottom. The MBEC biofilm disinfection test has been standardized and validated as ASTM method E2799 (29). Both of these methods have been validated in interlaboratory studies.…”