Evaluation of disinfection and sterilization of reusable angioscopes with the duck hepatitis B model

Purpose: Nosocomial transmission of viral hepatitis and retrovirus infectio n has been reported. The expected risk is greatest for the hepatitis B viru s (HBV). The duck HBV (DHBV) has similar biologic and structural characteri stics to HBV and has been adopted as a suitable model for disinfectant test ing. Methods: Angioscopic examination of the external jugular vein was performed on DHBV-infected ducks. After use, the instrument was air dried for 3 minu tes. Samples were obtained by flushing the channel with 5 mt of phosphate b uffered saline solution. The samples were collected immediately after dryin g (control), after flushing with 5 mt of water, after glutaraldehyde disinf ection for 5, 10, and 20 minutes, and after ethylene oxide gas sterilizatio n. Angioscopes were either predeaned or uncleaned before disinfection/steri lization. Residual infectivity was assessed with inoculation of samples int o the peritoneal cavity of day-old ducks (n = 231). Results: DNA analysis results of liver samples showed that all 38 control d ucks became infected. The frequency of DHBV infection was reduced to 93% (1 4 of 15) by flushing the angioscope with 5 mt of sterile water. No transmis sion occurred after the use of any of the properly precleaned and disinfect ed/sterilized angioscopes. However, after the use of the uncleaned angiosco pes, the transmission rate was 90% (9 of 10) and 70% (7 of 10) after 5 and 10 minutes of contact time, respectively, in 2% glutaraldehyde. Even after the recommended 20 minutes of contact time, there was still 6% (2 of 35) tr ansmission. After ethylene oxide sterilization, two of the recipient duckli ngs (2 of 35) were infected with DHBV. Conclusion: There was no disease transmission after reuse of disposable ang ioscopes adequately cleaned before disinfection or sterilization. However, if the angioscopes are inadequately cleaned, DHBV can survive despite gluta raldehyde disinfection or ethylene oxide sterilization. This contrasts with previous in vitro and in vivo data with solid surgical instruments. It is postulated that the presence of a narrow lumen or residual protein shieldin g within the lumen may compromise effective inactivation of hepadnaviruses on angioscopes, with the potential risk for patient-to-patient transmission .