A Novel Method to Sterilize Isolators for the Housing of Germ-Free Birds and Production of Germ-Free Eggs

Introduction

The effective sterilization of isolators prior to placement of germ-free birds/eggs is crucial to ensuring that the environment is free of potential contaminants. With the use of formaldehyde for sterilization becoming less popular owing to its carcinogenicity, the need for an alternative agent with the same efficacy is essential in the preparation of isolators. Chlorine dioxide dry gas has previously been shown to be a highly effective sterilization method, providing a promising alternative for germ-free avian egg facilities.

Methods

Polyvinyl chloride (PVC; n = 32) and stainless-steel production isolators (n = 7) were sterilized using approximately 4 h of exposure to chlorine dioxide (PVC isolator) and after approximately 6 h of exposure to chlorine dioxide (stainless-steel production isolator).

Results

Each isolator type was sterilized effectively using chlorine dioxide. Samples collected for microbiological analysis from the isolators after sterilization confirmed that the isolators were sterilized and remained sterile for at least 3 weeks after sterilization.

Discussion

The results of this study highlight the first use of chlorine dioxide dry gas for germ-free avian sterilization practices, augmenting on its use as a fogging agent seen in germ-free mice practices. As described in previous animal laboratory studies, values >1440 ppm-h cycle achieved in this study provided consistently adequate antimicrobial efficacy for the sterilization of germ-free egg facilities.

Conclusion

Chlorine dioxide dry gas is a highly effective sterilization solution for germ-free avian egg facilities, providing long-lasting sterility to isolators without the safety concerns associated with other fumigants such as formaldehyde.

Chlorine Dioxide Dry Gas: A Promising Solution for Effective Decontamination of Cephalosporin Compounds

Introduction

Cephalosporins can trigger hypersensitivity reactions in certain individuals. Consequently, strict regulations restrict the production of non-beta-lactam substances during or after cephalosporin manufacturing. Dry chlorine dioxide gas (dClO2), together with ultra-performance liquid chromatography Mass spectrometry/mass spectrometry (UPLC-MS/MS) detection methods, has emerged as a promising method for decontaminating cephalosporin compounds. This study aimed to assess whether a standardized dClO2 and testing protocol could provide successful decontamination of a broad spectrum of cephalosporins while also providing an indicative assessment of degradants and their biological activity.

Methods

Chemical indicators (CIs) mimicking different surfaces (stainless steel, Perspex®, aluminum) were contaminated with 1 μg/cm2 of each cephalosporin and exposed to 9600 ppm-h of dClO2, followed by UPLC-MS/MS analysis (phase 1). Cephalosporins underwent degradation assessment after exposure to ClO2 in an aqueous solution (phase 2). In total, 100μg of each compound was subjected to 400 ppm of dClO2 for 24 h (9600 ppm-h), followed by UPLC-MS/MS analysis. Antimicrobial susceptibility disks (30 μg) of cefaclor underwent identical treatment cycles and UPLC-MS/MS analysis. Subsequently, these disks were placed in Escherichia coli cultures to evaluate the biological activities of the degradants.

Results

The 9600 ppm-h of ClO2 exposure effectively degraded all cephalosporin compounds to levels <0.002 μg/cm2 on surfaces (phase 1), <2 ppb in solution, and <0.02 μg/disk (phase 2). The antimicrobial efficacy of cefaclor was nullified after the same exposure, confirming complete inactivation of the degradants.

Conclusion

A decontamination protocol utilizing dClO2, combined with UPLC-MS/MS and biological activity testing, has significant potential to enable facility repurposing for the production of non-beta-lactam compounds.

An overview of the bacterial microbiome of public transportation systems-risks, detection, and countermeasures

When we humans travel, our microorganisms come along. These can be harmless but also pathogenic, and are spread by touching surfaces or breathing aerosols in the passenger cabins. As the pandemic with SARS-CoV-2 has shown, those environments display a risk for infection transmission. For a risk reduction, countermeasures such as wearing face masks and distancing were applied in many places, yet had a significant social impact. Nevertheless, the next pandemic will come and additional countermeasures that contribute to the risk reduction are needed to keep commuters safe and reduce the spread of microorganisms and pathogens, but also have as little impact as possible on the daily lives of commuters. This review describes the bacterial microbiome of subways around the world, which is mainly characterized by human-associated genera. We emphasize on healthcare-associated ESKAPE pathogens within public transport, introduce state-of-the art methods to detect common microbes and potential pathogens such as LAMP and next-generation sequencing. Further, we describe and discuss possible countermeasures that could be deployed in public transportation systems, as antimicrobial surfaces or air sterilization using plasma. Commuting in public transport can harbor risks of infection. Improving the safety of travelers can be achieved by effective detection methods, microbial reduction systems, but importantly by hand hygiene and common-sense hygiene guidelines.

The in situ efficacy of whole room disinfection devices: a literature review with practical recommendations for implementation

BACKGROUND

Terminal cleaning and disinfection of hospital patient rooms must be performed after discharge of a patient with a multidrug resistant micro-organism to eliminate pathogens from the environment. Terminal disinfection is often performed manually, which is prone to human errors and therefore poses an increased infection risk for the next patients. Automated whole room disinfection (WRD) replaces or adds on to the manual process of disinfection and can contribute to the quality of terminal disinfection. While the in vitro efficacy of WRD devices has been extensively investigated and reviewed, little is known about the in situ efficacy in a real-life hospital setting. In this review, we summarize available literature on the in situ efficacy of WRD devices in a hospital setting and compare findings to the in vitro efficacy of WRD devices. Moreover, we offer practical recommendations for the implementation of WRD devices.

METHODS

The in situ efficacy was summarized for four commonly used types of WRD devices: aerosolized hydrogen peroxide, H₂O₂ vapour, ultraviolet C and pulsed xenon ultraviolet. The in situ efficacy was based on environmental and clinical outcome measures. A systematic literature search was performed in PubMed in September 2021 to identify available literature. For each disinfection system, we summarized the available devices, practical information, in vitro efficacy and in situ efficacy.

RESULTS

In total, 54 articles were included. Articles reporting environmental outcomes of WRD devices had large variation in methodology, reported outcome measures, preparation of the patient room prior to environmental sampling, the location of sampling within the room and the moment of sampling. For the clinical outcome measures, all included articles reported the infection rate. Overall, these studies consistently showed that automated disinfection using any of the four types of WRD is effective in reducing environmental and clinical outcomes.

CONCLUSION

Despite the large variation in the included studies, the four automated WRD systems are effective in reducing the amount of pathogens present in a hospital environment, which was also in line with conclusions from in vitro studies. Therefore, the assessment of what WRD device would be most suitable in a specific healthcare setting mostly depends on practical considerations.

Aerosolized Hydrogen Peroxide Decontamination of N95 Respirators, with Fit-Testing and Viral Inactivation, Demonstrates Feasibility for Reuse during the COVID-19 Pandemic

In response to the demand for N95 respirators by health care workers during the COVID-19 pandemic, we evaluated decontamination of N95 respirators using an aerosolized hydrogen peroxide (aHP) system. This system is designed to dispense a consistent atomized spray of aerosolized, 7% hydrogen peroxide (H₂O₂) solution over a treatment cycle. Multiple N95 respirator models were subjected to 10 or more cycles of respirator decontamination, with a select number periodically assessed for qualitative and quantitative fit testing. In parallel, we assessed the ability of aHP treatment to inactivate multiple viruses absorbed onto respirators, including phi6 bacteriophage, herpes simplex virus 1 (HSV-1), coxsackievirus B3 (CVB3), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). For pathogens transmitted via respiratory droplets and aerosols, it is critical to address respirator safety for reuse. This study provided experimental validation of an aHP treatment process that decontaminates the respirators while maintaining N95 function. External National Institute for Occupational Safety & Health (NIOSH) certification verified respirator structural integrity and filtration efficiency after 10 rounds of aHP treatment. Virus inactivation by aHP was comparable to the decontamination of commercial spore-based biological indicators. These data demonstrate that the aHP process is effective, with successful fit-testing of respirators after multiple aHP cycles, effective decontamination of multiple virus species, including SARS-CoV-2, successful decontamination of bacterial spores, and filtration efficiency maintained at or greater than 95%. While this study did not include extended or clinical use of N95 respirators between aHP cycles, these data provide proof of concept for aHP decontamination of N95 respirators before reuse in a crisis-capacity scenario.

IMPORTANCE The COVID-19 pandemic led to unprecedented pressure on health care and research facilities to provide personal protective equipment. The respiratory nature of the SARS-CoV2 pathogen makes respirator facepieces a critical protective measure to limit inhalation of this virus. While respirator facepieces were designed for single use and disposal, the pandemic increased overall demand for N95 respirators, and corresponding manufacturing and supply chain limitations necessitated the safe reuse of respirators when necessary. In this study, we repurposed an aerosolized hydrogen peroxide (aHP) system that is regularly utilized to decontaminate materials in a biosafety level 3 (BSL3) facility, to develop a method for decontamination of N95 respirators. Results from viral inactivation, biological indicators, respirator fit testing, and filtration efficiency testing all indicated that the process was effective at rendering N95 respirators safe for reuse. This proof-of-concept study establishes baseline data for future testing of aHP in crisis-capacity respirator-reuse scenarios.

Hydrogen Peroxide Vapor Decontamination of Hazard Group 3 Bacteria and Viruses in a Biosafety Level 3 Laboratory

Aim

This study aimed to validate the efficacy of hydrogen peroxide vapor (HPV) decontamination technology set up in a biosafety level 3 (BSL-3) laboratory on surrogates and hazard group 3 (HG3) agents.

Methods and Results

The HPV decontamination system (Bioquell) was assessed with both qualitative and quantitative methods on (1) spore surrogates (Geobacillus stearothermophilus, Bacillus atrophaeus, and Bacillus thuringiensis) in the BSL-3 laboratory and in the material airlock and on (2) HG3 agents (Bacillus anthracis; SARS-CoV-2, Venezuelan equine encephalitis virus [VEE], and Vaccinia virus) in the BSL-3 laboratory. Other HG3 bacteria likely to be handled in the BSL-3 laboratory (Yersinia pestis, Burkholderia mallei, Brucella melitensis, and Francisella tularensis) were excluded from the HPV decontamination assays as preliminary viability tests demonstrated the total inactivation of these agents after 48 h drying on different materials.

Conclusions

The efficacy of HPV decontamination was validated with a reduction in viability of 5-7 log10 for the spores (surrogates and B. anthracis), and for the enveloped RNA viruses. Vaccinia showed a higher resistance to the decontamination process, being dependent on the biological indicator location in the BSL-3 laboratory.

Analysis of Range and Use of a Hybrid Hydrogen Peroxide System for Biosafety Level 3 and Animal Biosafety Level 3 Agriculture Laboratory Decontamination

Introduction

The applications of fumigation and the challenges that high-containment facilities face in achieving effective large volume decontamination are well understood. The Biosecurity Research Institute at Kansas State University sought to evaluate a novel system within their biosafety level 3 (BSL-3) and animal biosafety level 3 agriculture (ABSL-3Ag) facility.

Methods

The system chosen for this study is the CURIS® Hybrid Hydrogen PeroxideTM (HHPTM) system, comprising a mobile 36-pound (16 kg) device delivering a proprietary 7% hydrogen peroxide (H2O2) solution. To examine the system's efficacy in multiple laboratory settings, two BSL-3 laboratories (2,281 [65 m3] and 4,668 ft3 [132 m3]) with dropped ceiling interstitial spaces and an ABSL-3Ag necropsy suite (44,212 ft3 [1,252 m3]) with 21-foot (6.4 m) ceilings were selected. Biological indicators (BIs) of Geobacillus stearothermophilus (1.7 × 106 organisms) on steel spore carriers and H2O2 chemical indicators (CIs) were used to provide validation.

Results

After cycle optimization, the smaller laboratory had a total of 60 BIs over two treatments that demonstrated a greater than 6-log reduction of bacterial spores. The larger laboratory (192 BIs) and the necropsy suite (206 BIs) had no BIs positive for spore growth when incubated at 60°C for 24 h per manufacturer's specifications.

Conclusion

Overall successful results through multiple components of this study demonstrate that the HHP device, paired with the pulsed 7% H2O2 solution, achieved efficacy regardless of variables in laboratory size and layout. Perceived challenges such as 21-ft (6.4 m) ceiling heights, active equipment, and difficult to access ceiling interstitial spaces proved unfounded. Given the successful sterilization of all challenged BIs, the HHP system presents a useful alternative for high level decontamination within BSL-3 and ABSL-3Ag facilities.

Validation of the Decontamination of a Specialist Transport System for Patients with High Consequence Infectious Diseases

When transferring highly infective patients to specialist hospitals, safe systems of work minimise the risk to healthcare staff. The EpiShuttle is a patient transport system that was developed to fit into an air ambulance. A validated decontamination procedure is required before the system can be adopted in the UK. Hydrogen peroxide (H2O2) vapour fumigation may offer better penetration of the inaccessible parts than the liquid disinfectant wiping that is currently suggested. To validate this, an EpiShuttle was fumigated in a sealed test chamber. Commercial bacterial spore indicators (BIs), alongside organic liquid suspensions and dried surface samples of MS2 bacteriophage (a safe virus surrogate), were placed in and around the EpiShuttle, for the purpose of evaluation. The complete kill of all of the BIs in the five test runs demonstrated the efficacy of the fumigation cycle. The log reduction of the MS2 that was dried on the coupons ranged from 2.66 to 4.50, but the log reduction of the MS2 that was in the organic liquids only ranged from 0.07 to 1.90, confirming the results of previous work. Fumigation with H2O2 alone may offer insufficient inactivation of viruses in liquid droplets, therefore a combination of fumigation and disinfectant surface wiping was proposed. Initial fumigation reducing contamination with minimal intervention allows disinfectant wipe cleaning to be completed more safely, with a second fumigation step inactivating the residual pathogens.

Public Buses Decontamination by Automated Hydrogen Peroxide Aerosolization System

BACKGROUND: Public transportation has been linked to an increase in the risk of coronavirus disease 2019 transmission. The effective decontamination system using aerosolized hydrogen peroxide can mitigate the transmission risk from using public transportation. AIM: The aim of this study was to develop and validate an effective decontamination system for public transport. METHODS: The experimental research was performed in 13 inter-city public buses. The aerosol generator with ultrasonic atomizer was used in the experiment. The validation process for disinfection was conducted using both a chemical indicator (CI) and spore discs biological indicator (inoculated with 106 Geobacillus stearothermophilus enclosed in glassine envelopes). The CIs and biological indicators were marked by number and placed in nine locations on each bus. The decontamination cycle was developed by analyzed of various aerosolized and decomposition period. Both concentrations of hydrogen peroxide, 5% and 7%, were used for comparison. RESULTS: In an aerosolized period, both concentrations of hydrogen peroxide at 30 min were effective for sporicidal 6-log reductions. The decontamination cycle totaled 100 min, based on a 70 min average decomposition time. CONCLUSIONS: The automated hydrogen peroxide aerosolized system is a highly effective and safe method of decontaminating public buses.

Decontamination of Bacillus Spores with Formaldehyde Vapor under Varied Environmental Conditions

Introduction

This study investigated formaldehyde decontamination efficacy against dried Bacillus spores on porous and non-porous test surfaces, under various environmental conditions. This knowledge will help responders determine effective formaldehyde exposure parameters to decontaminate affected spaces following a biological agent release.

Methods

Prescribed masses of paraformaldehyde or formalin were sublimated or evaporated, respectively, to generate formaldehyde vapor within a bench-scale test chamber. Adsorbent cartridges were used to measure formaldehyde vapor concentrations in the chamber at pre-determined times. A validated method was used to extract the cartridges and analyze for formaldehyde via liquid chromatography. Spores of Bacillus globigii, Bacillus thuringiensis, and Bacillus anthracis were inoculated and dried onto porous bare pine wood and non-porous painted concrete material coupons. A series of tests was conducted where temperature, relative humidity, and formaldehyde concentration were varied, to determine treatment efficacy outside of conditions where this decontaminant is well-characterized (laboratory temperature and humidity and 12 mg/L theoretical formaldehyde vapor concentration) to predict decontamination efficacy in applications that may arise following a biological incident.

Results

Low temperature trials (approximately 10°C) resulted in decreased formaldehyde air concentrations throughout the 48-hour time-course when compared with formaldehyde concentrations collected in the ambient temperature trials (approximately 22°C). Generally, decontamination efficacy on wood was lower for all three spore types compared with painted concrete. Also, higher recoveries resulted from painted concrete compared to wood, consistent with historical data on these materials. The highest decontamination efficacies were observed on the spores subjected to the longest exposures (48 hours) on both materials, with efficacies that gradually decreased with shorter exposures. Adsorption or absorption of the formaldehyde vapor may have been a factor, especially during the low temperature trials, resulting in less available formaldehyde in the air when measured.

Conclusion

Environmental conditions affect formaldehyde concentrations in the air and thereby affect decontamination efficacy. Efficacy is also impacted by the material with which the contaminants are in contact.

Airborne Disinfection by Dry Fogging Efficiently Inactivates Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Mycobacteria, and Bacterial Spores and Shows Limitations of Commercial Spore Carriers

Airborne disinfection is not only of crucial importance for the safe operation of laboratories and animal rooms where infectious agents are handled but also can be used in public health emergencies such as the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. We show that dry fogging an aerosolized mixture of peroxyacetic acid and hydrogen peroxide (aPAA-HP) is highly microbicidal, efficient, fast, robust, environmentally neutral, and a suitable airborne disinfection method.

Airborne disinfection of high-containment facilities before maintenance or between animal studies is crucial. Commercial spore carriers (CSC) coated with 10⁶ spores of Geobacillus stearothermophilus are often used to assess the efficacy of disinfection. We used quantitative carrier testing (QCT) procedures to compare the sensitivity of CSC with that of surrogates for nonenveloped and enveloped viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), mycobacteria, and spores, to an aerosolized mixture of peroxyacetic acid and hydrogen peroxide (aPAA-HP). We then used the QCT methodology to determine relevant process parameters to develop and validate effective disinfection protocols (≥4-log₁₀ reduction) in various large and complex facilities. Our results demonstrate that aPAA-HP is a highly efficient procedure for airborne room disinfection. Relevant process parameters such as temperature and relative humidity can be wirelessly monitored. Furthermore, we found striking differences in inactivation efficacies against some of the tested microorganisms. Overall, we conclude that dry fogging a mixture of aPAA-HP is highly effective against a broad range of microorganisms as well as material compatible with relevant concentrations. Furthermore, CSC are artificial bioindicators with lower resistance and thus should not be used for validating airborne disinfection when microorganisms other than viruses have to be inactivated.

IMPORTANCE Airborne disinfection is not only of crucial importance for the safe operation of laboratories and animal rooms where infectious agents are handled but also can be used in public health emergencies such as the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. We show that dry fogging an aerosolized mixture of peroxyacetic acid and hydrogen peroxide (aPAA-HP) is highly microbicidal, efficient, fast, robust, environmentally neutral, and a suitable airborne disinfection method. In addition, the low concentration of dispersed disinfectant, particularly for enveloped viral pathogens such as SARS-CoV-2, entails high material compatibility. For these reasons and due to the relative simplicity of the procedure, it is an ideal disinfection method for hospital wards, ambulances, public conveyances, and indoor community areas. Thus, we conclude that this method is an excellent choice for control of the current SARS-CoV-2 pandemic.

Effect of water activity on inactivation of Listeria monocytogenes using gaseous chlorine dioxide - A kinetic analysis

The aim of this study was to investigate the effect of water activity (a_w) on inactivation of Listeria monocytogenes using gaseous chlorine dioxide (ClO_{2 (g)}) under room temperature. Surface-inoculated tryptic soy agar (TSA) plates adjusted to 9 different water activity levels ranging from 0.994 to 0.429 were used as samples exposed to ClO_{2 (g)} at 150, 250, and 350 ppm for different durations of treatment time. Results showed that the antimicrobial effect of ClO_{2 (g)} significantly decreases as the a_w level and ClO_{2 (g)} concentration decrease. Nonlinear models, such as the modified Chick model and the Weibull model, were used to describe the inactivation kinetics of L. monocytogenes. The results showed that the modified Chick model, which is based on chemical reaction kinetics, was more suitable to describe the inactivation of L. monocytogenes (RMSE < 0.5 log CFU/g) than the Weibull model (RMSE < 1.0 log CFU/g). A multiple regression model was developed for the describing the effect of a_w and ClO_{2 (g)} concentration on bacterial inactivation. The results of this study may be used to design ClO_{2 (g)} treatment processes to inactivate L. monocytogenes in low-moisture foods.

The Hitchhiker's Guide to Hydrogen Peroxide Fumigation, Part 1: Introduction to Hydrogen Peroxide Fumigation

Introduction

When working with pathogens in laboratories, animal or production facilities, and even hospitals, the potential need for room fumigation for decontamination purposes must be taken into consideration. Questions regarding the choice of fumigant, technical aspects of the room, its ventilation, the fumigation system to be used, and other issues will arise and will have to be addressed.

Methods

This article is based on literature searches and was compiled using the authors' long-time personal experience in room and filter fumigation using various fumigation systems.

Results

The article can be used as a guide to establish an effective fumigation system in a laboratory or an animal facility setting and may be adapted for use in hospitals. Different systems for hydrogen peroxide fumigation on the market are presented. Also, technical aspects are discussed.

Discussion

Hydrogen peroxide is used in various forms for fumigation of rooms, equipment, and filters. Regardless of the individual limitations of these forms, hydrogen peroxide is a versatile fumigation method. However, it is important to consider numerous technical requirements when planning to implement hydrogen peroxide fumigation at an institution.

Conclusions

Subsequent to the present overview of different fumigation systems based on hydrogen peroxide on the market and their technical requirements, part 2 of this article will focus on validation and verification of hydrogen peroxide fumigation while considering the entire fumigation process. The two parts together will serve users as a guide to establishing hydrogen peroxide fumigations at their facilities.

Photolysis-driven indoor air chemistry following cleaning of hospital wards

Effective cleaning techniques are essential for the sterilization of rooms in hospitals and industry. No-touch devices (NTDs) that use fumigants such as hydrogen peroxide (H₂ O₂ ), formaldehyde (HCHO), ozone (O₃ ), and chlorine dioxide (OClO) are a recent innovation. This paper reports a previously unconsidered potential consequence of such cleaning technologies: the photochemical formation of high concentrations of hydroxyl radicals (OH), hydroperoxy radicals (HO₂ ), organic peroxy radicals (RO₂ ), and chlorine radicals (Cl) which can form harmful reaction products when exposed to chemicals commonly found in indoor air. This risk was evaluated by calculating radical production rates and concentrations based on measured indoor photon fluxes and typical fumigant concentrations during and after cleaning events. Sunlight and fluorescent tubes without covers initiated photolysis of all fumigants, and plastic-covered fluorescent tubes initiated photolysis of only some fumigants. Radical formation was often dominated by photolysis of fumigants during and after decontamination processes. Radical concentrations were predicted to be orders of magnitude greater than background levels during and immediately following cleaning events with each fumigant under one or more illumination condition. Maximum predicted radical concentrations (1.3 × 10⁷ molecule cm^-3 OH, 2.4 ppb HO₂ , 6.8 ppb RO₂ and 2.2 × 10⁸ molecule cm^-3 Cl) were much higher than baseline concentrations. Maximum OH concentrations occurred with O₃ photolysis, HO₂ with HCHO photolysis, and RO₂ and Cl with OClO photolysis. Elevated concentrations may persist for hours after NTD use, depending on the air change rate and air composition. Products from reactions involving radicals could significantly decrease air quality when disinfectants are used, leading to adverse health effects for occupants.

Room Decontamination Using Ionized Hydrogen Peroxide Fog and Mist Reduces Hatching Rates of Syphacia obvelata Ova

This study evaluated the efficacy of ionized hydrogen peroxide (iHP) fog and mist for environmental and surface decontamination of Syphacia obvelata ova in rodent rooms. Ova were collected by perianal tape impression from S. obvelata infected mice. In experiment 1, ova were exposed to iHP using a whole-room fogging decontamination system with a 15 min initial fog application cycle in unoccupied rodent rooms. Ova were removed from the fogged environment after a 15 min, 30 min, 90 min, or 240 min iHP exposure time. In experiment 2, a second cohort of ova were exposed to iHP using the whole-room fogging decontamination system. Ova were removed after 3, 4 or 6 continuous fog application cycles with 45 min dwelling time between each cycle and 15 h dwelling time for the last time point. In experiment 3, a third set of ova was exposed to an iHP surface misting unit with 1, 2, or 3 iHP mist applications. A 7 min contact time followed each application. After exposure, ova were incubated in a hatching medium for 6 h. Control ova were maintained at room temperature without iHP exposure before incubation in the hatching medium. After incubation, the number of ova hatched was assessed by microscopic examination. For experiment 1, results ranged from 46% to 57% of exposed ova hatched. For experiment 2, results ranged from 43% to 49% of ova hatched. For experiment 3, 37% to 46% of exposed ova hatched. Conversely, for the control groups above 80% of ova hatched for all 3 experiments. These data suggest that exposure to iHP fog and mist has variable effectiveness in reducing viability of S. obvelata ova at the time points tracked. Further studies are needed to identify iHP exposures that will further reduce or eliminate the hatching of rodent pinworm ova.

Decontamination of Bacillus Spores with Formaldehyde Vapor Under Varied Environmental Conditions

Introduction:

This effort investigated formaldehyde vapor characteristics under various environmental conditions by the analyses of air samples collected over a time-course. This knowledge will help responders achieve desired formaldehyde exposure parameters for decontamination of affected spaces after a biological contamination incident.

Methods:

Prescribed masses of paraformaldehyde and formalin were sublimated or evaporated, respectively, to generate formaldehyde vapor. Adsorbent cartridges were used to collect air samples from the test chamber at predetermined times. A validated method was used to extract the cartridges and analyze for formaldehyde via liquid chromatography. In addition, material demand for the formaldehyde was evaluated by inclusion of arrays of Plexiglas panels in the test chamber to determine the effect of varied surface areas within the test chamber. Temperature was controlled with a circulating water bath connected to a radiator and fan inside the chamber. Relative humidity was controlled with humidity fixed-point salt solutions and water vapor generated from evaporated water.

Results:

Low temperature trials (approximately 10°C) resulted in decreased formaldehyde air concentrations throughout the 48-hour time-course when compared with formaldehyde concentrations in the ambient temperature trials (approximately 22°C). The addition of clear Plexiglas panels to increase the surface area of the test chamber interior resulted in appreciable decreases of formaldehyde air concentration when compared to an empty test chamber.

Conclusion:

This work has shown that environmental variables and surface-to-volume ratios in the decontaminated space may affect the availability of formaldehyde in the air and, therefore, may affect decontamination effectiveness.

Formaldehyde Vapor Characteristics in Varied Decontamination Environments

Introduction:

This effort investigated formaldehyde vapor characteristics under various environmental conditions by the analyses of air samples collected over a time-course. This knowledge will help responders achieve desired formaldehyde exposure parameters for decontamination of affected spaces after a biological contamination incident.

Methods:

Prescribed masses of paraformaldehyde and formalin were sublimated or evaporated, respectively, to generate formaldehyde vapor. Adsorbent cartridges were used to collect air samples from the test chamber at predetermined times. A validated method was used to extract the cartridges and analyze for formaldehyde via liquid chromatography. In addition, material demand for the formaldehyde was evaluated by inclusion of arrays of Plexiglas panels in the test chamber to determine the impact of varied surface areas within the test chamber. Temperature was controlled with a circulating water bath connected to a radiator and fan inside the chamber. Relative humidity was controlled with humidity fixed-point salt solutions and water vapor generated from evaporated water.

Results:

Low temperature trials (approximately 10°C) resulted in decreased formaldehyde air concentrations throughout the 48-hour time-course when compared with formaldehyde concentrations in the ambient temperature trials (approximately 22°C). The addition of clear Plexiglas panels to increase the surface area of the test chamber interior resulted in appreciable decreases of formaldehyde air concentration when compared to an empty test chamber.

Conclusion:

This work has shown that environmental variables and surface-to-volume ratios in the decontaminated space may affect the availability of formaldehyde in the air and, therefore, may affect decontamination effectiveness.

Comparing the Efficacy of Formaldehyde with Hydrogen Peroxide Fumigation on Infectious Bronchitis Virus

BACKGROUND

The recent reclassification of formaldehyde as a presumed carcinogen prompted the investigation into the comparative efficacy of hydrogen peroxide as a fumigant in microbiological safety cabinets.

INTRODUCTION

The aim of the study was to quantify the biocidal efficacy of formaldehyde fumigation, including variables such as exposure time and concentration, and then to compare this to the biocidal efficacy achieved from a hydrogen peroxide vapor fumigation system. The study also investigated the ability of both fumigants to permeate the microbiological safety cabinet (MBSC), including the workspace, under the work tray, and after the HEPA filters. Furthermore, the effect of organic soiling on efficacy was also assessed. Infectious bronchitis virus (IBV) was used as the biological target to develop this study model.

METHODS

A model using IBV was developed to determine the efficacy of formaldehyde and hydrogen peroxide as fumigants. Virus was dried on stainless steel discs, and variables including concentration, time, protein soiling, and location within an MBSC were assessed.

RESULTS

It was demonstrated that formaldehyde fumigation could achieve a 6-log reduction in the titer of the virus throughout the cabinet, and high protein soiling in the presentation did not affect efficacy. Appropriate cycle parameters for the hydrogen peroxide system were developed, and when challenged with IBV, it was shown that vaporized hydrogen peroxide could achieve an equal 6-log titer reduction as formaldehyde within the cabinet workspace and overcome the presence of soiling.

CONCLUSION

Hydrogen peroxide was demonstrated to be a viable alternative to formaldehyde under most situations tested. However, the hydrogen peroxide system did not achieve an equal titer reduction above the cabinet's first HEPA filter using the cabinet workspace cycle, and further optimization of the hydrogen peroxide cycle parameters, including pulsing of the cabinet fans, may be required to achieve this.

Performance Testing of a Venturi-Based Backpack Spray Decontamination System

Introduction

The performance of 2 disinfectant chemicals, peracetic acid (PAA) and hypochlorous acid (HOCl), was evaluated using a Venturi-nozzle-based light decontamination system (LDS) for delivery. The atomization equipment combined low-pressure air and disinfectant via a handheld lance, producing a fine, dense aerosol. A range of microorganisms, including Bacillus cereus and Bacillus anthracis (Vollum) spores, were used as test challenges to evaluate chemicals and equipment.

Methods

The tests undertaken included assessments over fixed and variable exposure times, use of multiple surface materials, and a live agent challenge.

Results

Over a fixed-time exposure of 60 minutes, aerosolized PAA gave 7- to 8-log reductions of all test challenges, but HOCl was less effective. Material tests showed extensive kill on most surfaces using PAA (≥6-log kill), but HOCl showed more variation (4- to 6-log). Testing using B. anthracis showed measurable PAA induced spore kill inside 5 minutes and >6-log kill at 5 minutes or over. HOCl was less effective.

Discussion

The results demonstrate the importance of testing decontamination systems against a range of relevant microbiological challenges. Disinfectant efficacy may vary depending on product choice, types of challenge microorganisms, and their position in a treated area. The most effective disinfectants demonstrate biocidal efficacy despite these factors.

Conclusion

The data confirmed PAA as an effective disinfectant capable of rapidly killing a range of microorganisms, including spores. HOCl was less effective. The LDS system successfully delivered PAA and HOCl over a wide area and could be suitable for a range of frontline biosecurity applications.

Chlorine gas is an effective alternative to sterilize carnation leaves for Fusarium spp. identification

Sterile carnation leaves are required for proper morphological identification of Fusarium spp. but the gamma irradiation equipment required for leaf sterilization is not available to everyone. This study evaluated three different methods for sterilizing carnation leaves: microwave radiation, ultraviolet, and chlorine gas (CG) sterilization. Both microwave and ultraviolet treatments did not sufficiently sterilize leaf tissue, however, exposure to CG for 2 h resulted in no growth of either fungi or bacteria. Exposure times of carnation leaves to CG were also evaluated for spore production, spore size and morphological characteristics of five Fusarium spp. Only carnation leaves exposed to CG for 45, 60 or 90 min were completely free of microorganism contamination. There were some differences in spore production and size, however, no differences were observed for characteristics essential for proper species identification such as micro- and macrospore features and production of sporodochia, perithecia, chlamydospores, and phialides for any of the CG exposure times. This study identified leaves sterilized by CG as a reliable substitute for gamma irradiation sterilization. The method described here is suitable for most laboratories and will provide a means for Fusarium identification when gamma irradiated leaves are not available.

An overview of automated room disinfection systems: When to use them and how to choose them

Conventional disinfection methods are limited by reliance on the operator to ensure appropriate selection, formulation, distribution, and contact time of the agent. Automated room disinfection (ARD) systems remove or reduce reliance on operators and so they have the potential to improve the efficacy of terminal disinfection. The most commonly used systems are hydrogen peroxide vapor (H₂O₂ vapor), aerosolized hydrogen peroxide (aHP), and ultraviolet (UV) light. These systems have important differences in their active agent, delivery mechanism, efficacy, process time, and ease of use. The choice of ARD system should be influenced by the intended application, the evidence base for effectiveness, practicalities of implementation, and cost considerations.

Case Study: Room Fumigation Using Aerosolized Hydrogen Peroxide-A Versatile and Economic Fumigation Method

Introduction

Formaldehyde is still the method of choice for fumigation of rooms and HEPA filters at high- and maximum-containment facilities because of its proven track record and low cost. However, formaldehyde has been shown to be carcinogenic and should ideally be replaced by other, less hazardous methods. This change has in part been hampered by the relatively high cost of alternative methods.

Methods

Here, we provide examples of room fumigations using aerosolized hydrogen peroxide showing not only that it can be used economically but also that it is a versatile method and may be used under circumstances not normally suited for fumigation.

Results and Discussion

Four examples of fumigation setups are presented that illustrate the versatility, ease of use, and adaptability of aerosolized hydrogen peroxide as a fumigant. In addition, we demonstrate that aerosolized hydrogen peroxide passes through HEPA filters in biological safety cabinets and individually ventilated cage racks.

Conclusions

Considering that the fumigation method presented here is simple and highly effective, we expect it to serve as a relatively cost-effective alternative to formaldehyde fumigation for disinfecting potentially contaminated rooms and surfaces.

Opinion: Airtightness for Decontamination by Fumigation of High-Containment Laboratories

INTRODUCTION

While the European legislation states that laboratories of high-containment must be sealable for fumigation, they do not prescribe a minimal value for airtightness. Starting from a previous study in which we measured the airtightness in 4 BSL-3 laboratories with blower-door tests, we discuss the connection between airtightness and a successful decontamination by fumigation.

METHODS

Biological indicators (BIs) consisting of spores of Geobacillus stearothermophilus on metal disks were laid out in laboratories of different levels of airtightness before performing a fumigation with aerosolized hydrogen peroxide using an automated device, according to the manufacturer's instructions.

RESULTS

Incubation of all BI disks placed in the facility with the highest level of airtightness showed complete inactivation of spores. However, in the facility with a lower level of airtightness, not all spores were inactivated.

DISCUSSION

Air leaks might be a factor in the outcome of the decontamination of a room by fumigation, as seen in the laboratory with a lower level of airtightness, but other factors associated with the fumigation process might also be critical for a successful decontamination.

CONCLUSION

We argue that a validation of the decontamination procedure, before first use or after important renovations of a laboratory of high-containment, is a more effective endpoint than reaching a predefined level of airtightness.

Hazard Group 3 agent decontamination using hydrogen peroxide vapour in a class III microbiological safety cabinet

AIMS

This study investigated the efficacy of hydrogen peroxide vapour (HPV) at inactivating hazard group 3 bacteria that have been presented dried from their growth medium to present a realistic challenge.

METHODS AND RESULTS

Hydrogen peroxide vapour technology (Bioquell) was used to decontaminate a class III microbiological safety cabinet containing biological indicators (BIs) made by drying standard working suspensions of the following agents: Bacillus anthracis (Ames) spores, Brucella abortus (strain S99), Burkholderia pseudomallei (NCTC 12939), Escherichia coli O157 ST11 (NCTC 12079), Mycobacterium tuberculosis (strain H37Rv) and Yersinia pestis (strain CO92) on stainless steel coupons. Extended cycles were used to expose the agents for 90 min. The HPV cycle completely inactivated B. anthracis spores, B. abortus, B. pseudomallei, E. coli O157 and Y. pestis when BIs were processed using quantitative and qualitative methods. Whilst M. tuberculosis was not completely inactivated, it was reduced by 4 log₁₀ from a starting concentration of 10⁶ colony-forming units.

CONCLUSIONS

This study demonstrates that HPV is able to inactivate a range of HG3 agents at high concentrations with associated organic matter, but M. tuberculosis showed increased resistance to the process.

SIGNIFICANCE AND IMPACT OF THE STUDY

This publication demonstrates that HPV can inactivate HG3 agents that have an organic load associated with them. It also shows that M. tuberculosis has higher resistance to HPV than other agents. This shows that an appropriate BI to represent the agent of interest should be chosen to demonstrate a decontamination is successful.

Review of Decontamination Techniques for the Inactivation of Bacillus anthracis and Other Spore-Forming Bacteria Associated with Building or Outdoor Materials

Since the intentional release of Bacillus anthracis spores through the U.S. Postal Service in the fall of 2001, research and development related to decontamination for this biological agent have increased substantially. This review synthesizes the advances made relative to B. anthracis spore decontamination science and technology since approximately 2002, referencing the open scientific literature and publicly available, well-documented scientific reports. In the process of conducting this review, scientific knowledge gaps have also been identified. This review focuses primarily on techniques that are commercially available and that could potentially be used in the large-scale decontamination of buildings and other structures, as well as outdoor environments. Since 2002, the body of scientific data related to decontamination and microbial sterilization has grown substantially, especially in terms of quantifying decontamination efficacy as a function of several factors. Specifically, progress has been made in understanding how decontaminant chemistry, the materials the microorganisms are associated with, environmental factors, and microbiological methods quantitatively impact spore inactivation. While advancement has been made in the past 15 years to further the state of the science in the inactivation of bacterial spores in a decontamination scenario, further research is warranted to close the scientific gaps that remain.

Disinfection efficiency of positive pressure respiratory protective hood using fumigation sterilization cabinet

Concerns have been raised about both the disinfection and the reusability of respiratory protective equipment following a disinfection process. Currently, there is little data available on the effects of disinfection and decontamination on positive pressure respiratory protective hoods (PPRPH). In this study, we evaluated the effect of vaporized hydrogen peroxide (VHP) on the disinfection of PPRPH to determine applicability of this method for disinfection of protective equipment, especially protective equipment with an electric supply system.

A hydrogen peroxide-based fumigation sterilization cabinet was developed particularly for disinfection of protective equipment, and the disinfection experiments were conducted using four PPRPHs hung in the fumigation chamber. The pathogenic microorganism Geobacillus stearothermophilus ATCC 7953 was used as a biological indicator in this study and the relationship between air flow (the amount of VHP) and disinfection was investigated. Both function and the material physical properties of the PPRPH were assessed following the disinfection procedure. No surviving Geobacillus stearothermophilus ATCC 7953, both inside and outside of these disinfected PPRPHs, could be observed after a 60 min treatment with an air flow of 10.5–12.3 m³/h. Both function and material physical properties of these PPRPHs met the working requirements after disinfection.

This study indicates that air flow in the fumigation chamber directly influences the concentration of VHP. The protective equipment fumigation sterilization cabinet developed in this paper achieves the complete sterilization of the PPRPHs when the air flow is at 10.5–12.3 m³/h, and provides a potential solution for the disinfection of various kind of protective equipment.

Plasma-Activated Aerosolized Hydrogen Peroxide (aHP) in Surface Inactivation Procedures

Introduction

Hydrogen peroxide is a strong oxidant that possesses an antimicrobial activity. It has been successfully used in surface/room decontamination processes either under the form of hydrogen peroxide vapor (HPV) or of vaporized hydrogen peroxide (VHP). Aerosolized hydrogen peroxide (aHP) offers a third alternative. The technology relies on the dispersion of aerosols of a hydrogen peroxide solution often complemented with silver cations. aHP provides an inexpensive and safe approach to treat contaminated rooms but sometimes fails to achieve the 6-log10 reduction limit in the number of viable microorganisms.

Methods

Here, we used a venturi-based aHP generator that generates 4 mm in size aerosols from a 12% plasma-activated hydrogen peroxide solution free of silver cations.

Results & Discussion

We could successfully and constantly inactivate bacterial growth from biological indicators containing at least 106 spores of Geobacillus stearothermophilus placed on stainless steel discs wrapped in Tyvek pouches. We could also show that the biological indicators placed at various locations in a class II biosafety cabinet were equally inactivated, showing that hydrogen peroxide aerosols migrate through HEPA filters.

Conclusions

Considering that our method for aerosol generation is simple, reproducible, and highly effective at inactivating spores, our approach is expected to serve as a relatively cost effective alternative method for disinfecting potentially contaminated rooms or surfaces.

Whole room disinfection with hydrogen peroxide mist to control Listeria monocytogenes in food industry related environments

Listeria monocytogenes surviving daily cleaning and disinfection is a challenge for many types of food industries. In this study, it was tested whether whole room disinfection (WRD) with H₂O₂ mist could kill L. monocytogenes under conditions relevant for the food industry. Survival of a mixture of four L. monocytogenes strains exposed to H₂O₂ mist was investigated in a 36 m³ room. A commercial machine produced H₂O₂ mist by pumping a 5% H₂O₂ solution containing 0.005% silver through a nozzle, and breaking the liquid up in droplets using pressurized air. When a suspension of bacteria in 0.9% NaCl applied on stainless steel coupons was exposed to WRD with H₂O₂ mist, a >5 log reduction (LR) of L. monocytogenes was observed. Similar reductions were observed in all tests with conditions between 12 and 20 °C, H₂O₂ concentrations of 35-80 ppm and 1-2 h exposure. It was shown that the H₂O₂ in the mist dissolved and accumulated in the liquid on the steel, and acted against L. monocytogenes in the liquid phase. At high cell concentrations, the effect was reduced if cells were pregrown at highly aerated conditions. The anti-listerial effect was robust against protein and fat, but the effect was quenched by raw meat and raw salmon, probably due to high catalase activity. The effect of whole room disinfection with H₂O₂ against dried L. monocytogenes cells was 1-2 LR, however the effect of air-drying by itself lead to 3-4 LR. When biofilms were exposed to WRD, no surviving L. monocytogenes were observed on stainless steel, however for L. monocytogenes on a PVC conveyor belt material, there were surviving bacteria, with about 2 LR. Screening of 54 L. monocytogenes strains for growth susceptibility to H₂O₂ showed that their sensitivity to H₂O₂ was very similar, thus WRD with H₂O₂ are likely to be robust against strain variation in susceptibility to H₂O₂. Production of H₂O₂ mist resulted in increased room humidity, and this may limit the maximum H₂O₂ concentration achievable, especially at low temperatures. The results in this study show that whole room disinfection with H₂O₂ may have potential to control L. monocytogenes in the food industry, however intervention studies in the food industry are needed to verify the effect in practical use.

Evaluation of an Environmental Monitoring Program for the Microbial Safety of Air and Surfaces in a Dairy Plant Environment

Microbiological hazards can occur when foodstuffs come into contact with contaminated surfaces or infectious agents dispersed by air currents in the manufacturing environment. An environmental monitoring program (EMP) is a critical aspect of sustainable and safe food manufacturing used to evaluate the effectiveness of the microbial controls in place. An effective EMP should be based on risk analysis, taking into account previous sampling history to determine the selection of the sampling points, the scope of the test, and the frequency of analysis. This study involved evaluation of the environmental monitoring regime and microbiological status of a medium-sized dairy plant manufacturing food ingredients, e.g., proteins, milk powders, and dairy fats. The data specific to microbial tests ( n = 3,468), recorded across 124 fixed sampling locations over a 2-year period (2014 to 2015) from air ( n = 1,787) and surfaces ( n = 1,681) were analyzed. The aim of this study was to highlight the strengths and weaknesses of the EMP in a select dairy processing plant. The results of this study outline the selection of sampling locations, the scope of the test, and the frequency of analysis. An analysis of variance revealed subsections of the manufacturing areas with high risk factors, especially the packaging subsection specified for bulk packaging, the atomizer, and the fluidized bed. The temporal and spatial analysis showed the potential to reduce or relocate the monitoring effort, most notably related to total coliforms and Staphylococcus aureus, across the dairy plant due to homogeneity across the sampling subsections with little or no deviations. The results suggest a need to reevaluate the current EMP and the corrective action plan, especially with regard to detection of pathogens. Recommendations for optimization of the EMP are presented to assist the dairy industry with reviewing and revising the control measures and hazard assessment with regard to existing contamination issues.

Evaluating the efficacy of hydrogen peroxide vapour against foot-and-mouth disease virus within a BSL4 biosafety facility

An evaluation was made of the efficacy of 35% hydrogen peroxide vapour (HPV) against foot-and-mouth disease virus (FMDV) in a biosafety facility. Biological indicators (BIs) were produced using three serotypes of FMDV, all with a titre of ≥10⁶ TCID₅₀ per ml. Fifteen BIs of each serotype were distributed across five locations, throughout a 30-m³ airlock chamber, producing a total of 45 BIs. Thirty-five percent HPV was generated and applied using a Bioquell vaporization module located in the centre of the chamber. After a dwell period of 40 min, the HPV was removed via the enclosures air handling system and the BIs were collected. The surfaces of the BIs were recovered into Glasgow's modified Eagle's medium (GMEM), cultivated in BHK21 Cl13 cell culture and analysed for evidence of cytopathic effect (CPE). No CPE was detected in any BI sample. Positive controls showed CPE. The experimentation shows that FMDV is susceptible to HPV decontamination and presents a potential alternative to formaldehyde.

SIGNIFICANCE AND IMPACT OF THE STUDY

Foot-and-mouth disease virus (FMDV) is an important pathogen in terms of biosafety due to its infectious nature and wide range of host animals, such as cattle, sheep, goats and pigs. Outbreaks of FMDV can have a severe impact on livestock production, causing morbidity, mortality, reduced yields and trade embargoes. Laboratories studying FMDV must possess BSL4 robust bio-decontamination methods to prevent inadvertent release. Formaldehyde has been the primary agent for environmental decontamination, but its designation as a human carcinogen has led to a search for alternatives. This study shows 35% hydrogen peroxide vapour has the potential to be a rapid, effective, residue-free alternative.

Microorganisms in Confined Habitats: Microbial Monitoring and Control of Intensive Care Units, Operating Rooms, Cleanrooms and the International Space Station

Indoor environments, where people spend most of their time, are characterized by a specific microbial community, the indoor microbiome. Most indoor environments are connected to the natural environment by high ventilation, but some habitats are more confined: intensive care units, operating rooms, cleanrooms and the international space station (ISS) are extraordinary living and working areas for humans, with a limited exchange with the environment. The purposes for confinement are different: a patient has to be protected from infections (intensive care unit, operating room), product quality has to be assured (cleanrooms), or confinement is necessary due to extreme, health-threatening outer conditions, as on the ISS. The ISS represents the most secluded man-made habitat, constantly inhabited by humans since November 2000 – and, inevitably, also by microorganisms. All of these man-made confined habitats need to be microbiologically monitored and controlled, by e.g., microbial cleaning and disinfection. However, these measures apply constant selective pressures, which support microbes with resistance capacities against antibiotics or chemical and physical stresses and thus facilitate the rise of survival specialists and multi-resistant strains. In this article, we summarize the available data on the microbiome of aforementioned confined habitats. By comparing the different operating, maintenance and monitoring procedures as well as microbial communities therein, we emphasize the importance to properly understand the effects of confinement on the microbial diversity, the possible risks represented by some of these microorganisms and by the evolution of (antibiotic) resistances in such environments – and the need to reassess the current hygiene standards.

Decontamination of a BSL3 laboratory by hydrogen peroxide fumigation using three different surrogates for Bacillus anthracis spores

AIMS

Two independent trials investigated the decontamination of a BSL3 laboratory using vaporous hydrogen peroxide and compared the effect on spores of Bacillus cereus, Bacillus subtilis and Bacillus thuringiensis as surrogates for Bacillus anthracis spores, while spores of Geobacillus stearothermophilus served as control.

METHODS AND RESULTS

Carriers containing 1·0 × 10(6) spores were placed at various locations within the laboratory before fumigation with hydrogen peroxide following a previously validated protocol. Afterwards, carriers were monitored by plating out samples on agar and observing enrichment in nutrient medium for up to 14 days. Three months later, the experiment was repeated and results were compared. On 98 of 102 carriers, no viable spores could be detected after decontamination, while the remaining four carriers exhibited growth of CFU only after enrichment for several days. Reduction factors between 4·0 and 6·0 log levels could be reached.

CONCLUSIONS

A validated decontamination of a laboratory with hydrogen peroxide represents an effective alternative to fumigation with formaldehyde. Spores of B. cereus seem to be more resistant than those of G. stearothermophilus.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results of this study provide important results in the field of hydrogen peroxide decontamination when analysing the effect on spores other than those of G. stearothermophilus.

A guide to no-touch automated room disinfection (NTD) systems

Conventional disinfection methods are limited by reliance on the operator to ensure appropriate selection, formulation, distribution and contact time of the agent. ‘No-touch’ automated room disinfection (NTD) systems remove or reduce reliance on operators and so they have the potential to improve the efficacy of terminal disinfection. The most commonly used systems are hydrogen peroxide vapour (H₂O₂ vapour), aerosolised hydrogen peroxide (aHP) and ultraviolet (UV) radiation. These systems have important differences in their active agent, delivery mechanism, efficacy, process time and ease of use. The choice of NTD system should be influenced by the intended application, the evidence base for effectiveness, practicalities of implementation and cost constraints.

Decontamination of a hospital room using gaseous chlorine dioxide: Bacillus anthracis, Francisella tularensis, and Yersinia pestis

This study assessed the efficacy of gaseous chlorine dioxide for inactivation of Bacillus anthracis, Francisella tularensis, and Yersinia pestis in a hospital patient care suite. Spore and vegetative cells of Bacillus anthracis Sterne 34F2, spores of Bacillus atrophaeus ATCC 9372 and vegetative cells of both Francisella tularensis ATCC 6223 and Yersinia pestis A1122 were exposed to gaseous chlorine dioxide in a patient care suite. Organism inactivation was then assessed by log reduction in viable organisms postexposure to chlorine dioxide gas compared to non-exposed control organism. Hospital room decontamination protocols utilizing chlorine dioxide gas concentrations of 377 to 385 ppm maintained to exposures of 767 ppm-hours with 65% relative humidity consistently achieved complete inactivation of B. anthracis and B. atrophaeus spores, as well as vegetative cells of B. anthracis, F. tularensis, and Y. pestis. Decrease in exposure (ppm-hours) and relative humidity (<65%) or restricting airflow reduced inactivation but achieved >8 log reductions in organisms. Up to 10-log reductions were achieved in a hospital room with limited impact on adjacent areas, indicating chlorine dioxide concentrations needed for decontamination of highly concentrated (>6 logs) organisms can be achieved throughout a hospital room. This study translates laboratory chlorine dioxide fumigation studies applied in a complex clinical environment.

The role of 'no-touch' automated room disinfection systems in infection prevention and control

BACKGROUND

Surface contamination in hospitals is involved in the transmission of pathogens in a proportion of healthcare-associated infections. Admission to a room previously occupied by a patient colonized or infected with certain nosocomial pathogens increases the risk of acquisition by subsequent occupants; thus, there is a need to improve terminal disinfection of these patient rooms. Conventional disinfection methods may be limited by reliance on the operator to ensure appropriate selection, formulation, distribution and contact time of the agent. These problems can be reduced by the use of 'no-touch' automated room disinfection (NTD) systems.

AIM

To summarize published data related to NTD systems.

METHODS

Pubmed searches for relevant articles.

FINDINGS

A number of NTD systems have emerged, which remove or reduce reliance on the operator to ensure distribution, contact time and process repeatability, and aim to improve the level of disinfection and thus mitigate the increased risk from the prior room occupant. Available NTD systems include hydrogen peroxide (H(2)O(2)) vapour systems, aerosolized hydrogen peroxide (aHP) and ultraviolet radiation. These systems have important differences in their active agent, delivery mechanism, efficacy, process time and ease of use. Typically, there is a trade-off between time and effectiveness among NTD systems. The choice of NTD system should be influenced by the intended application, the evidence base for effectiveness, practicalities of implementation and cost constraints.

CONCLUSION

NTD systems are gaining acceptance as a useful tool for infection prevention and control.