Evaluation of the ability of different detergents and disinfectants to remove and kill organisms in traditional biofilm

Background: The objective of this study was to assess the ability of different detergent and disinfectant combinations to eradicate bacteria in traditional biofilm. Methods: Enterococcus faecalis and Pseudomonas aeruginosa were used to develop biofilm over 8 days. The biofilm on each minimum biofilm eradication concentration peg contained 8 log(10) colony forming units (CFU)/cm(2) of both bacteria. The detergents evaluated were as follows: Prolystica Enzymatic 2X, Prolystica Neutral 2X, Neodisher, and Endozime Bio-Clean. The disinfectants evaluated were as follows: glutaraldehyde, accelerated hydrogen peroxide, and ortho-phthalaldehyde. Biofilm removal was evaluated using viable count, protein and carbohydrate quantitation, and scanning electron microscopy. Results: Only Prolystica Enzymatic 2X and Endozime Bio-Clean killed both E faecalis (3.90 log(10) CFU/mL reduction) and P aeruginosa (3.96 log(10) CFU/mL reduction) in suspension. None of the detergents tested could provide >1 log(10) CFU/cm(2) reduction for bacteria within biofilm. Any combination of detergent and high-level disinfectant reduced the level of both E faecalis and P aeruginosa within biofilm by 3-5 log(10) CFU/cm(2). Although the combination of Endozime Bio-Clean and glutaraldehyde provided a 6 log(10) reduction, it could not eliminate both bacteria within biofilm. Conclusions: Our data indicate that if biofilm accumulates in flexible endoscope channels during repeated rounds of reprocessing, then neither the detergent nor high-level disinfectant will provide the expected level of bacterial removal or killing. (C) 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.