PR26 *TESTING BIOFILM REMOVAL

Abstract

Purpose: Currently there are no standards for testing efficacy of medical device cleaners. With fears of prion transmission, reliable protein on medical devices needs to be minimised.Aim: To develop a reliable test to detect efficacy of biofilm removal which can be used as an industry standard.Methodology: A bioreactor model was used to grow a characterised Pseudomonas aeruginosa strain on Teflon coupons. The coupons were subjected to various cleaners. Residual biofilm was detected by either a crystal violet assay (CV) or protein assay (PA). The % reduction of biofilm was compared to controls including analysis of variance and student t‐tests. Each experiment was repeated three times. Inter and intra‐experimental comparisons were made. Visual confirmation of the results was by confocal microscopy and scanning electron microscopy.Results: NaOH 1% 40C for 30 min: CV 87.3% ± 5.4, PA 92.0% ± 2.3; NaOH 0.01N 70C for 5 min: PA 28.4% ± 2.7; Tween20 40C for 30 min: CV 25.1 ± 2.7, PA 14.5 ± 5.7 (not significant). Some representative commercial cleaners were tested. Matrix: CV 10.5% ± 3.7, PA 27.9% ± 3.0; RMEC 70500: CV 69.0% ± 4.5, PA 85.9% ± 2.9; Zen: PA 105.8% ± 1.5 (i.e. treatment coupons were cleaner than background coupons). All treatments were significant p < 0.05 except for Tween20, which was not consistently significant. There was no significant inter‐experimental difference for % reduction.Conclusions: We have developed a reproducible method for testing efficacy of cleaning products against biofilm incorporating the use of crystal violet or protein assay to measure residual biofilm protein.