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.