Removal of biofilm from endoscopes: Evaluation of detergent efficiency Karen Vickery, BVSc, MVSc, PhD, Aniko Pajkos, BSc, and Yvonne Cossart, MB BS, BSc (Med), FRCPA Sydney, New South Wales, Australia Background: Biofilm consisting of bacteria enclosed in a matrix of exopolysaccharide (EPS) forms on many medical devices such as catheters and implants. Nosocomial infection is, thus, a newly recognized scenario of biofilm development. Biofilm removal by physical methods such as ultrasound and mechanical cleaning is reasonably effective but difficult to supervise in practice. Chemical methods are often ineffective because of biofilm resistance to biocides. In this study, we compared the efficiency of different detergents used in endoscope reprocessing. Methods: Escherichia coli biofilm was generated on Teflon and medical grade PVC tubing under low flow conditions. Sections of biofilm covered tubing were washed using test detergents and biofilm removal was assessed by counting remaining adherent bacteria after washing and by scanning electron microscopy to qualitatively assess the amount and nature of the remaining biofilm. Results: Control tubing developed a multilayered biofilm consisting of >10 5 bacterial cells/cm 2 . Only Matrix (Whiteley Medical, Sydney, Australia) produced >4 log reduction in viable bacterial numbers. Matrix and Epizyme Rapid (3M Australia, Pymble, Australia) were able to remove up to 75% and 60% of the biofilm, respectively. Conclusions: Many commonly used enzymatic cleaners fail to reduce the viable bacterial load or remove the bacterial EPS. Cleaners with high enzyme activity, Epizyme Rapid, removed more biofilm but failed to reduce bacterial numbers more than 2 logs. The only cleaner containing no enzymes, Matrix, significantly reduced bacterial viability and residual bacterial EPS. (Am J Infect Control 2004;32:170-6.) Bacteria readily adhere to wet surfaces and form organized colonies of cells enclosed in a self-excreted matrix composed principally of polysaccharide (EPS) that facilitates adhesion to the surface and each other. This type of bacterial organization is termed biofilm and was originally noted in 1936. 1 Fouling and corrosion of plant and pipework by biofilms has been a major problem for industry 2 ; however, despite their early discovery, it has only been relatively recently that their major impact on infection control has been realized. Biofilm can form on or in many medical devices such as contact lenses, central venous cathe- ters, urinary catheters, 3 and breast implants 4 and frequently results in nosocomial infection with implant loss and associated increase in patient morbidity and health care costs. We have recently demonstrated biofilm in clinically used dental syringes 5 and endo- scopes (unpublished observations). Removal of biofilm poses considerable difficulties in the hospital environment. Although physical methods such as ultrasonication and mechanical cleaning or scraping are generally effective if carried out effi- ciently, chemical methods are often ineffective be- cause of the resistance of biofilms to antibiotics, disinfectants, and biocides. Bacteria within biofilms are up to 1000 times more resistant to antimicrobials than the same bacteria in suspension. 6,7 To date, efficacy testing of new biocides is conducted against bacteria in suspension or dried onto carriers, although government regulatory organizations are beginning to demand ‘‘in use’’ testing. Similarly, testing of deter- gents has only been against soil dried onto a surface rather than against biofilm that is expected to be many more times tenaciously attached to the surface. This may account for failure of decontamination procedures despite strict attention to protocols. 8,9 From the Department of Infectious Diseases, University of Sydney, and The Australian Centre for Hepatitis Virology. This research was funded by NH&MRC grant 9937934 and Whiteley Industries Pty Ltd. Aniko Pajkos was in receipt of a APAI Postraguate Industry Award, and Karen Vickery was in receipt of a NH&MRC Australian Postdoctoral Clinical Fellowship. The work was performed in the Department of Infectious Diseases and Immunology, University of Sydney, Sydney, New South Wales 2006, Australia. Reprint requests: Karen Vickery, PhD, Department of Infectious Diseases and Immunology, University of Sydney, Sydney NSW 2006 Australia. 0196-6553/$30.00 Copyright ª 2004 by the Association for Professionals in Infection Control and Epidemiology, Inc. doi:10.1016/j.ajic.2003.10.009 170