Comparative evaluation of four hydrogen peroxide-based systems to decontaminate N95 respirators

Comparison of 2 methods for sterilization of filtering facepiece respirators worn for extended periods during the COVID-19 pandemic: An experimental laboratory study

BACKGROUND

During the COVID-19 pandemic, there was a shortage of filtering facepiece respirators (FFR), leading to prolonged use and reuse of FFRs.

METHODS

FFRs were collected in 3 hospitals after extended use (up to 15 or 30days). We assessed the physical characteristics and filtration levels of worn FFRs, before sterilization. Respirators that achieved at least 94% filtration of aerosol particles, nasal clip still attached, had no tears, had preserved elastic bands, and had no dirt were randomized to receive or not receive cleaning before being submitted to hydrogen peroxide plasma gas sterilization.

RESULTS

A total of 1,055 FFRs were collected. Over 85% of them exhibited secured nose clips, preserved strap elasticity, and no tears. However, more than 78% of samples contained dirt, leaving only 101 (19.6%) eligible to undergo sterilization. After sterilization, none of the FFRs in either group achieved minimum filtration, although 72% without cleaning and 80% with cleaning had filtration between 90.0% and 93.9%.

DISCUSSION

A large proportion of FFRs were ineligible for sterilization due to factors unrelated to health care (eg, dirt from makeup).

CONCLUSIONS

Prolonged reuse of FFRs significantly reduced aerosol filtration efficiency. Eligible FFRs did not maintain 94% filtration after sterilization with or without cleaning.

Color changing bioadhesive barrier for peripherally inserted central catheters

Bacteria migration at catheter insertion sites presents a serious complication (bacteraemia) with high mortality rates. One strategy to mediate bacteraemia is a physical barrier at the skin-catheter interface. Herein a colorimetric biosensor adhesive (CathoGlu) is designed and evaluated for both colorimetric detection of bacterial infection and application as a bacteria barrier. The design intent combines viscous, hydrophobic bioadhesive with an organic pH indicator (bromothymol blue). Visual observation can then distinguish healthy skin at pH = ∼5 from an infected catheter insertion site at pH = ∼8. The liquid-to-biorubber transition of CathoGlu formulation occurs via a brief exposure to UVA penlight, providing an elastic barrier to the skin flora. Leachates from CathoGlu demonstrate no genotoxic and skin sensitization effect, assessed by OECD-recommended in vitro and in chemico assays. The CathoGlu formulation was found non-inferior against clinically approved 2-octyl-cyanoacrylate (Dermabond™), and adhesive tape (Micropore™) within an in vivo porcine model. CathoGlu skin adhesive provides new opportunities to prevent sepsis in challenging clinical situations.

Advanced Oxidative Decontamination of Flax and Its Impacts on Storage

The metabolic actions of storage fungi and other microorganisms can cause spoilage and post-harvest losses in agricultural commodities, including flaxseed. These microbial contaminants are oxidized with hydroxyl radicals that are efficiently generated when ozone, hydrogen peroxide (H2O2) and ultraviolet (UV) light react in an advanced oxidative process (AOP). The present work explores what we believe is the first application of an AOP technology to reduce mould on whole brown and yellow flaxseed. The impact of AOP on storage and quality parameters was assessed by measuring the fatty acid value (FAV), germination rate, moisture content (MC) and visible mould growth after 12 weeks of storage at 30°C and 75% relative humidity (RH). Under these conditions, the yellow decontaminated flaxseed showed a 31% decrease in the number of seeds with visible mould without any adverse effect on germination rate, FAV and MC. In contrast, the same AOP treatment created an insignificant decrease in mould in stored brown flaxseed, at the cost of decreasing the germination rate and increasing FAV. The adverse effects of AOP on brown flaxseed were not readily apparent but became measurable after storage. Moreover, Fourier transform infrared (FTIR) spectroscopy was utilized to explore the rationale behind the different reactions of flaxseed varieties to AOP. The corresponding results indicated that the tolerance of yellow flaxseed to AOP might be related to its richness in olefins. The authors believe that technologies that harness advanced oxidative processes open new horizons in decontamination beyond ozone alone and towards increasing the shelf life of various agri-food products.

Plasma-generated reactive water mist for disinfection of N95 respirators laden with MS2 and T4 bacteriophage viruses

Due to the shortage of personal protective equipment (PPE) during the COVID-19 pandemic, the interest and demand for sterilization devices to reuse PPE has increased. For reuse of face masks, they must be effectively decontaminated of potential infectious agents without compromising its filtration ability during sterilization. In this study, we utilized an atmospheric pressure pulsed dielectric barrier discharge (DBD), combined with nebulized liquid microdroplets to generate plasma-activated mist (PAM). MS2 and T4 bacteriophages were used to conduct the decontamination tests on two types of N95 respirators. Results showed at least a 2-log reduction of MS2 and T4 on N95 respirators treated in one cycle with 7.8% hydrogen peroxide PAM and at least a 3-log reduction treated in 10% hydrogen peroxide PAM. In addition, it was found that there was no significant degradation in filtration efficiency of N95 respirators (3M 1860 and 1804) treated in 10% hydrogen peroxide PAM found after 20 cycles. In terms of re-useability of masks after treatment as determined, it was shown that the elastic straps of 3M 1804 were fragmented after 20 treatment cycles rendering them unusable, while the straps of 3M 1860 were not negatively affected even after 20 disinfection cycles.