The decontamination cycle was started and the Minidox-M successfully raised the chamber’s RH to 65 percent, whereby both the chamber and its contents were held at 65 percent RH for 30 minutes. At the completion of this dwell period, the single set of three control BIs were extracted via BI ports on the isolator to avoid any contact with CD. These BIs were immediately incubated in modified soybean casein digest broth for seven days at 57 degrees Celsius.
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Explore This IssueApril/May 2014
Following “Condition,” the Minidox-M stepped into “Charge” and injected CD gas until its concentration reached 1.0 mg/L. Upon satisfying its set point, “Exposure” began and the CD gas was held inside the chamber for exactly 720 ppm-hrs. At the completion of “Exposure” the carbon scrubber was energized and any gas inside the chamber was evacuated within a matter of a few minutes. Once concentrations were reduced to 0.0 mg/L, the Minidox-M prompted for cycle completion, at which time the 18 experimental BIs were retrieved. The six sets of three BIs were then immediately incubated, just as the control BIs removed earlier, in modified soybean casein digest broth for seven days at 57 degrees Celsius.
After the seventh day of incubation, the set of three control BIs resulted in positive growth as expected; indicating that the specific lot of BIs used for this study were viable prior to any testing. Each set of three BIs covered with powdered milk, powdered baby formula, protein powder, flour, sugar, and grain, of that same lot, indicated no growth. The set of three BIs covered with the general dust/dirt also indicated no growth. This confirms that gaseous CD was able to penetrate all seven of the organic loads and still obtain a 6-log sporicidal reduction.
Bioburdens such as those tested have a notorious nature of providing refuge and sustenance for unwanted microbes. In a perfect world, any bioburden formed in a facility would be immediately and completely removed. However that is never the case, as it is nearly impossible for facilities to sufficiently clean every crack and crevasse on every wall, ceiling, and floor. As such, there is always some degree of buildup of bioburden somewhere in a facility. This buildup of bioburden creates a more difficult location to clean, as most decontamination methods would be impaired by the existence of bioburden.
Findings from this study did not provide a specific answer regarding how much bioburden needs to be removed prior to administering a decontaminating agent, or “how clean is clean.” The results do indicate visually however that gaseous CD is powerful enough to penetrate bioburden to some degree and still achieve a 6-log sporicidal reduction. See photo Examples 1 and 2 for an indication of how soiled a surface can be, with a select choice of bioburden, and still be successfully decontaminated with gaseous CD utilizing the standard cycle dosage. Consequently, the physical removal of significant bioburden remains a necessity while complete removal does not. Thus, even though the impracticality of cleaning every crack, crevasse, and cranny still persists, gaseous CD can be an ideal choice for combating bacteria living amongst overlooked bioburden.
Lorcheim, the director of operations for ClorDiSys Solutions, Inc., is a licensed professional engineer responsible for directing the commercialization and manufacturing of various decontamination and sterilization equipment for the pharmaceutical, life science, health care, and food industries. Reach him at firstname.lastname@example.org.