RE:RE:RE:RE:RE:RE:RE:RE:RE:RE:RE:Bernard & EchoTo be clear, all scopes goint forward should be cleaned according to the FDA's guidance published previously and published in detail for all end users earlier this year. The main purpose of this is to eliminate bioburden and make it easier to sterilize endoscopes, the duodenoscope in this case being the main scope of interest.
It is typical in these controlled studies to process 3 consecutive scopes for the submissions to FDA for extended claims. TSO3 does not set this standard, but this is the typical FDA standard for 510k submissions to validate terminal sterilization efficacy in a half cycle, simulated use cycle, and pat.
And, to be clear, the VP4 is not a typical H2O2 terminal sterilizer. It is a superior product
H2O2 + OZONE sterilizer. I refer you to the previously published paper [
Dufresne, S and Richards, T. The first dual-sterilant low-temperature sterilization system. Can J Infect Control. 2016; 31: 169–174 ] and www.tso3.com to see the science behind the process and why the addition of ozone adds sterilization capacity (to get into small long lumens and in the elevator mechanisms, for example) that other older technologies cannot address. Is the reason 3M has not submitted similar validation tests to the FDA because they haveand end users have found their ETO sterilizers, though apparently efficacious for completely properly cleaned scopes, do not sterilize in the presence of bioburden?
"Overkill (half-cycle) test method
The tested duodenoscope model was first evaluated in the hydrogen peroxide–ozone sterilizer with an overkill method performed in triplicate using 2 separate duodenoscopes. The overkill method (or half-cycle method) consists of inoculating the medical devices with more than 1.0×106 colony-forming units (CFU) of the most resistant organism identified for this sterilization process and by showing no growth after the half-cycle point of the sterilization cycle (cycle performed included 1 phase of sterilant exposure instead of 2 phases in a complete cycle). This results in a sterility assurance level of 10−6" "The inoculation sites tested as part of this overkill validation included the endoscope channels and elevator mechanism" Though serum was not added to the innoculum in this test , "No washing step was performed prior to sterilization."
To repeat, as I believe I have already posted this, they then tested 3 Olympus q180v duodenoscopes under worse case conditions with bioburden (hard H2O, serum, hardest to kill bacteria/spores) to again show efficacy even in the presence of bioburden:
"Simulated-use test method
The sterilization of the duodenoscope model was also evaluated in the hydrogen peroxide–ozone sterilizer with a simulated-use method performed in triplicate. Three separate duodenoscopes were used in this testing. When performing a simulated-use validation, the most resistant microorganism to the sterilization process is mixed with organic and inorganic soils and inoculated on devices. These simulated soils, including organic and inorganic compounds, mimic clinical use. The inoculated medical devices are not washed (thus simulating a worst-case scenario) and exposed to a complete cycle of the sterilization process.57 The intended use of the tested sterilizer stipulates that medical devices must be cleaned as per the manufacturer's instructions for use before sterilization. Nevertheless, the cleaning step is omitted in a simulated-use method to perform the test under worst-case conditions."
"Clinical in-use test method
A clinical in-use study was performed to evaluate the efficacy of processing clinically soiled duodenoscopes following the standard processing steps performed in a health care facility but with the terminal step being sterilization in the hydrogen peroxide–ozone sterilizer instead of HLD. Hospital-owned duodenoscopes were used during clinical procedures and assessed for their sterility after processing in the hydrogen peroxide–ozone sterilizer. Five separate duodenoscopes were used in the clinical study. The tested duodenoscopes were not in new condition. Signs of wear, including ridges on the insertion tube and cracks in the bending section, were visually observed. All tested duodenoscopes were taken from surgeries during which patients were not on an antimicrobial regimen at the time of the endoscopic retrograde cholangiopancreatography procedure, since antimicrobials could reduce the bioburden level on the endoscope post procedure and bias the results. Endoscopes from 11 surgical procedures were tested: endoscopes 1-3 to establish precleaning contamination levels, endoscopes 4-8 to establish post–manual cleaning contamination levels, and endoscopes 9-11 for poststerilization assessment."
I am not sure where you found that this AJIC study only tested 2 scopes in any of the testing protocols. I believe they used the FDA standard of 3 consecutive cycle in each validating testing protocol.