Efficacy of high-level disinfectants for reprocessing GI endoscopes in simulated-use testing

Background: There has been recent public concern regarding the adequacy of current practices for flexible endoscope reprocessing. High-level disinfection is defined by the Food and Drug Administration (FDA) as a minimum of 6-log reduction of mycobacteria under a worst-case scenario. Several agents are currently approved by the FDA, but published data on their relative efficacies against mycobacteria are lacking. The objective of this study was to determine the efficacy of these agents for high-level disinfection. Methods: In simulated-use testing, video endoscopes (5 colonoscopes and 5 duodenoscopes) were each inoculated with 9.0 × 107 colony-forming units of Mycobacterium chelonae. Cleaning was performed by using a standardized protocol. Each endoscope was then subjected to chemical disinfection with Cidex (2.0% glutaraldehyde) at 20°C for 20 minutes, Sporox (7.5% hydrogen peroxide) at 20° for 30 minutes, and Steris 20 (0.2% peracetic acid) at 50°C to 56°C for 12 minutes using the Steris System 1 processor. Although not FDA-approved, tests were also conducted by using 70% isopropyl alcohol at 20°C for 20 minutes. These results were compared with disinfection with ethylene oxide gas. All channels were sampled for M chelonae before and after manual cleaning and after disinfection. Results: Cleaning alone resulted in an average log reduction of 3. Cidex, Sporox, Steris 20, ethylene oxide gas, and isopropyl alcohol, in combination with manual cleaning, each achieved a 6-log or greater reduction of the mycobacterial inoculum. No organisms were recovered from any channel after reprocessing with ethylene oxide and Steris 20. Conclusions: Commercially available high-level disinfectants are equally efficacious for reprocessing flexible GI endoscopes when used in conjunction with cleaning and in accordance with recommended guidelines.