Low temperature vaporized hydrogen peroxide sterilization of 3D printed devices.

BACKGROUND: Low temperature vaporized hydrogen peroxide sterilization (VH2O2) is used in hospitals today to sterilize reusable medical devices. VH2O2 sterilized 3D printed materials were evaluated for sterilization, biocompatibility and material compatibility. MATERIALS & METHODS: Test articles were printed at Formlabs with BioMed Clear™ and BioMed Amber™, and at Stratasys with MED610™, MED615™ and MED620™. Sterilization, biocompatibility and material compatibility studies with 3D printed materials were conducted after VH2O2 sterilization in V-PRO™ Sterilizers. The overkill method was used to evaluate sterilization in a ½ cycle. Biocompatibility testing evaluated the processed materials as limited contact (< 24-hours) surface or externally communicating devices. Material compatibility after VH2O2 sterilization (material strength and dimensionality) was evaluated via ASTM methods and dimensional analysis. RESULTS: 3D printed devices, within a specific design window, were sterile after VH2O2 ½ cycles. After multiple cycle exposure, the materials were not cytotoxic, not sensitizing, not an irritant, not a systemic toxin, not pyrogenic and were hemo-compatible. Material compatibility via ASTM testing and dimensionality evaluations did not indicate any significant changes to the 3D printed materials after VH2O2 sterilization. CONCLUSION: Low temperature vaporized hydrogen peroxide sterilization is demonstrated as a suitable method to sterilize 3D printed devices. The results are a subset of the data used in a regulatory submission with the US FDA to support claims for sterilization of 3D printed devices with specified materials, printers, and device design 1.

Alcohol flush does not aid in endoscope channel drying but may serve as an adjunctive microbiocidal measure: A new take on an old assumption.

BACKGROUND: Alcohol is perceived to aid flexible endoscope channel drying, however we previously showed alcohol increased the time required to dry some channels with forced air versus water alone. Yet, alcohol may prevent microorganism outgrowth during storage. Drying endoscope channels has been shown to prevent outgrowth, but it is unknown if incomplete drying (<10 µL remaining) provides similar protection. METHODS: Endoscope channel test articles were used to determine the efficacy of 70%-30% alcohol flush for prevention of Pseudomonas aeruginosa outgrowth and drying efficiency. For non-alcohol flushed channels, the impact of forced air drying on outgrowth of P. aeruginosa was determined. RESULTS: Alcohol flush (70%-30%) prevented outgrowth with little to no recovery of P. aeruginosa during ambient storage. 70% alcohol increased channel drying time by 1.5 or 3-fold compared to 50% alcohol or water, respectively. Forced air drying of non-alcohol flushed channels greatly reduced the initial contamination level and prevented outgrowth. Incomplete drying of contaminated channels was akin to no application of forced air. Applying forced air for more time than necessary to remove residual liquid did not completely eliminate the low level recovery of P. aeruginosa. CONCLUSIONS: Flushing with reduced concentrations of alcohol may provide a strategy to prevent microbial outgrowth while reducing drying time.

Efficacy of flexible endoscope drying using novel endoscope test articles that allow direct visualization of the internal channel systems.

BACKGROUND: Thorough drying of flexible endoscope channels has been identified as an essential reprocessing step. Yet, instructions are not specific on how to dry endoscopes. There is lack of data supporting efficacy of current drying practices, due to limitations in determining channel dryness. METHODS: Novel endoscope test articles were used to evaluate the effectiveness of alcohol flush and hanging in an ambient endoscope storage cabinet. Prepared test articles were hung in a storage cabinet for 5 days and visually inspected for residual liquid. The procedure for preoperative inspection of endoscopic systems was performed to determine the procedure's efficacy for removing residual liquid. Then, testing was performed to assess the impact of pressure, residual liquid type and route of air application on time to dry using compressed air. RESULTS: Alcohol flush followed by hanging in an ambient storage cabinet was not effective for drying endoscope channels, and residual liquid was not completely removed after performing the steps of the preoperative inspection of endoscopic channels. The factors impacting effective compressed air drying were channel dependent. For some channels, alcohol increased the time to dry. CONCLUSIONS: Endoscope drying is complex; borescope evaluation does not ensure a dry device.

Novel methods for disinfection of prion-contaminated medical devices.

BACKGROUND: The unique resistance of prions to classic methods of decontamination, and evidence that prion diseases can be transmitted iatrogenically by medical devices pose a serious infection control challenge to health-care facilities. In view of the widespread tissue distribution of the variant Creutzfeldt-Jakob disease agent in human beings, new practicable decontamination procedures are urgently needed. METHODS: We adapted an in-vivo method using stainless steel wires contaminated with prions to the hamster-adapted scrapie strain 263K. A new in-vitro protocol of surface contamination compatible with subsequent biochemical detection of PrP(res) (protease-resistant form of the prion protein) from the treated surface was developed to explore the mechanisms of action of methods of decontamination under test. These models were used to investigate the effectiveness of innovative physical and chemical methods of prion inactivation. FINDINGS: Standard chemical decontamination methods (NaOH 1N, NaOCl 20000 ppm) and autoclaving in water at 134 degrees C reduced infectivity by >5.6 log10 lethal doses; autoclaving without immersion was somewhat less effective (4-4.5 log reduction). Three milder treatments, including a phenolic disinfectant, an alkaline cleaner, and the combination of an enzymatic cleaner and vaporised hydrogen peroxide (VHP) were also effective. VHP alone, which can be compatible with electronic components, achieved an approximately 4.5 log reduction in infectivity (equivalent to autoclaving without water immersion). INTERPRETATION: New decontamination procedures are proposed to ensure the safety of medical and surgical instruments as well as surfaces that cannot withstand the currently recommended prion inactivation procedures.