Mechanisms of Sporicidal Activity Induced by Ionized Hydrogen Peroxide in the Spores of Bacillus atrophaeus.

Introduction: Ionized hydrogen peroxide (iHP) is a new technology used for the decontamination of surfaces or laboratory areas. It utilizes a low concentration of hydrogen peroxide (H2O2) mixed with air and ionized through a cold plasma arc. This technology generates reactive oxygen species as a means of decontamination. Objectives: The purpose of this study is to review the effects of iHP on the structure of the spores of Bacillus atrophaeus by observing its effects using transmission electron microscopy (TEM) and also by evaluating the existence of DNA damage by fluorescence-based quantitative polymerase chain reaction (qPCR). Methods: Spore samples of B. atrophaeus decontaminated using iHP at different exposure times (Control, 1, 2, 6, and 12 h) were fixed for TEM. In addition, DNA was extracted for evaluation of DNA damages using fluorescence-based qPCR assays. Results: Damages to the spore structures of B. atrophaeus caused by the decontamination process with iHP at different exposure times (Control, 1, 2, 6, and 12 h) can be observed in micrographs. The effects of the decontamination to short DNA segment (132 base pairs [bp]) of the yaaH gene using qPCR present a linear degradation, and for the long DNA segment (680 bp), it presents a biphasic mode. Conclusion: The results of the qPCR analysis show two initial stages of damage to DNA with very noticeable damage at 12 h contact time, which confirms the observations of the TEM micrographs for the B. atrophaeus spores. The study demonstrates damage to the spore core DNA.

Determining the Effectiveness of Decontamination with Ionized Hydrogen Peroxide.

Introduction: Ionized Hydrogen Peroxide (iHP) is a new technology used for the decontamination of surfaces or laboratory areas. It utilizes a low concentration of hydrogen peroxide (H2O2) mixed with air and ionized through a cold plasma arc. This technology generates reactive oxygen species (ROS) as a means of decontamination. Objectives: The purpose of this study is to evaluate the diffusion effect of iHP and its decontamination capabilities using biological and enzyme indicators. Methods: A gas-tight fumigation room with a volume of 880 ft3 was used for the decontamination trials. During the decontamination process, empty animal cages were placed inside to create fumigant distribution restrictions. Spore and enzyme indicators were placed in eleven locations throughout the decontamination room. Generation of iHP was done with the use of TOMI's SteraMist Environmental System and the SteraMist Solution, with 7.8% H2O2 at a dose of 0.5 ml per ft3. Results: For the decontamination of 1hr, 2hrs, 6hrs, and 12hrs, the biological indicators of B. atrophaeus in Stainless Steel (SS) Disk in Tyvek envelope have an inactivation rate of 94%, 97%, 100%, and 100%, respectively. For G. stearothermophilus in SS disk and Tyvek envelope, it has 82%, 68%, 100%, and 100%, respectively and, for G. stearothermophilus in SS strips it has an effective rate of 88%, 67%, 91%, and 100%, respectively. Conclusion: iHP inactivates spores, and the residual tAK activity indicates a gas-like fumigant diffusion due to the uniformity of the inactivation without the use of oscillating fans as the contact time is extended.

Multicycle Autoclave Decontamination of N95 Filtering Facepiece Respirators.

Introduction: During pandemic situations like the one caused by the emergent coronavirus SARS-CoV-2, healthcare systems face the challenge of limited personal protective equipment and impaired supply chains. This problem poses a threat to healthcare workers, first responders, and the public, which demands solutions that can span the gap between institutional shortages and resupplies. Objectives: To examine the efficacy of autoclave-based decontamination for the reuse of single-use surgical masks and N95 filtering facepiece respirators (FFRs). This method is the most readily available form of decontamination in the hospital and laboratory settings. Methods: Three models of N95 FFRs and two procedural masks were evaluated in this study. A moist heat autoclave using four different autoclave cycles: 115°C for one hour, 121.1°C for 30 minutes, 130°C for two minutes, and 130°C for four minutes was used. After the autoclave process, the FFRs were NIOSH fit tested and particle counting was performed for both coarse particles of 5 micrometers (µM) and fine particles from 0.1µM to 1.0µM. Results: We observed negligible alterations in the functionality and integrity of 3M 1805 and 3M 1870/1870+ N95 FFRs after three autoclave cycles. Surgical masks also showed minimal changes in functionality and integrity. The 3M 1860 FFR failed fit test after a single autoclave decontamination cycle. Discussion and Conclusion: The study finds that specific surgical masks and N95 FFR models can withstand autoclave decontamination for up to three cycles. Additionally, the autoclave cycles tested were those that could be readily achieved by both clinical and research institutions.