A comparison of persistence of SARS-CoV-2 variants on stainless steel.

The survival of newer variants of SARS-CoV-2 on a representative surface has been compared to the established UK circulating isolate to determine whether enhanced environmental stability could play a part in their increased transmissibility. Stainless steel coupons were inoculated with liquid cultures of the three variants, with coupons recovered over seven days and processed for recoverable viable virus using plaque assay. After drying, there was no significant difference in inactivation rates between variants, indicating that there is no increased environmental persistence from the new variants.

Detection of SARS-CoV-2 within the healthcare environment: a multi-centre study conducted during the first wave of the COVID-19 outbreak in England.

BACKGROUND: Understanding how severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is spread within the hospital setting is essential in order to protect staff, implement effective infection control measures, and prevent nosocomial transmission. METHODS: The presence of SARS-CoV-2 in the air and on environmental surfaces around hospitalized patients, with and without respiratory symptoms, was investigated. Environmental sampling was undertaken within eight hospitals in England during the first wave of the coronavirus disease 2019 outbreak. Samples were analysed using reverse transcription polymerase chain reaction (PCR) and virus isolation assays. FINDINGS: SARS-CoV-2 RNA was detected on 30 (8.9%) of 336 environmental surfaces. Cycle threshold values ranged from 28.8 to 39.1, equating to 2.2 x 105 to 59 genomic copies/swab. Concomitant bacterial counts were low, suggesting that the cleaning performed by nursing and domestic staff across all eight hospitals was effective. SARS-CoV-2 RNA was detected in four of 55 air samples taken <1 m from four different patients. In all cases, the concentration of viral RNA was low and ranged from <10 to 460 genomic copies/m3 air. Infectious virus was not recovered from any of the PCR-positive samples analysed. CONCLUSIONS: Effective cleaning can reduce the risk of fomite (contact) transmission, but some surface types may facilitate the survival, persistence and/or dispersal of SARS-CoV-2. The presence of low or undetectable concentrations of viral RNA in the air supports current guidance on the use of specific personal protective equipment for aerosol-generating and non-aerosol-generating procedures.

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.

The transfer of unsterilized material from Mars to Phobos: Laboratory tests, modelling and statistical evaluation.

Sample return missions to Phobos are the subject of future exploration plans. Given the proximity of Phobos to Mars, Mars' potential to have supported life, and the possibility of material transfer from Mars to Phobos, careful consideration of planetary protection is required. If life exists, or ever existed, on Mars, there is a possibility that material carrying organisms could be present on Phobos and be collected by a sample return mission such as the Japanese Martian Moons eXplorer (MMX). Here we describe laboratory experiments, theoretical modelling and statistical analysis undertaken to quantify whether the likelihood of a sample from Phobos material containing unsterilized material transferred from Mars is less than 10-6, the threshold to transition between restricted and unrestricted sample return classification for planetary protection. We have created heat, impact and radiation sterilization models based on the Phobos environment, and through statistical analyses investigated the level of sterilization expected for martian material transferred to Phobos. These analyses indicate that radiation is the major sterilization factor, sterilizing the Phobos surface over timescales of millions of years. The specific events of most relevance in the Phobos sample return context are the 'young' cratering events on Mars that result in Zunil-sized craters, which can emplace a large mass of martian material on Phobos, in a short period of time, thus inhibiting the effects of radiation sterilization. Major unknowns that cannot yet be constrained accurately enough are found to drive the results - the most critical being the determination of exact crater ages to statistical certainty, and the initial biological loading on Mars prior to transfer. We find that, when taking a conservative perspective and assuming the best-case scenario for organism survival, for a 100 g sample of the Phobos regolith to be below the planetary protection requirement for unrestricted sample return, the initial biological loading on Mars must be <8.2 × 103cfu kg-1. For the planned MMX mission, a ∼10 g sample to be obtained from a 25-30 mm diameter core as planned would require an initial martian biological loading to be <1.6 × 104cfu kg-1, in order to remain compliant with the planetary protection threshold.

Drumming-associated anthrax incidents: exposures to low levels of indoor environmental contamination.

Two fatal drumming-related inhalational anthrax incidents occurred in 2006 and 2008 in the UK. One individual was a drum maker and drummer from the Scottish Borders, most likely infected whilst playing a goat-skin drum contaminated with Bacillus anthracis spores; the second, a drummer and drum maker from East London, likely became infected whilst working with contaminated animal hides.We have collated epidemiological and environmental data from these incidents and reviewed them alongside three similar contemporaneous incidents in the USA. Sampling operations recovered the causative agent from drums and drum skins and from residences and communal buildings at low levels. From these data, we have considered the nature of the exposures and the number of other individuals likely to have been exposed, either to the primary infection events or to subsequent prolonged environmental contamination (or both).Despite many individual exposures to widespread low-level spore contamination in private residences and in work spaces for extended periods of time (at least 1 year in one instance), only one other individual acquired an infection (cutaneous). Whilst recognising the difficulty in making definitive inferences from these incidents to specific residual contamination levels, and by extending the risk to public health, we believe it may be useful to reflect on these findings when considering future incident management risk assessments and decisions in similar incidents that result in low-level indoor contamination.

Sampling and inactivation of wet disseminated spores from flooring materials, using commercially available robotic vacuum cleaners.

AIMS: Four commercially available robotic vacuum cleaners were assessed for sampling efficiency of wet disseminated Bacillus atrophaeus spores on carpet, polyvinyl chloride (PVC) and laminate flooring. Furthermore, their operability was evaluated and decontamination efficiency of one robot was assessed, using a sodium hypochlorite solution. METHODS AND RESULTS: In an environmental chamber, robots self-navigated around 4 m2 of flooring containing a single contaminated 0·25 m2 tile (c. 104 spores per cm2 ). Contamination levels at predetermined locations were assessed by macrofoam swabs (PVC and laminate) or water soluble tape (carpet), before and after sampling. Robots were dismantled postsampling and spore recoveries assessed. Aerosol contamination was also measured during sampling. Robot sampling efficiencies were variable, however, robots recovered most spores from laminate (up to 17·1%), then PVC and lastly the carpet. All robots spread contamination from the 'hotspot' (all robots spread <0·6% of the contamination to other areas) and became surface contaminated. Spores were detected at low levels during air sampling (<5·6 spores per litre). Liquid decontamination inactivated 99·1% of spores from PVC. CONCLUSIONS: Robotic vacuum cleaners show promise for both sampling and initial decontamination of indoor flooring. SIGNIFICANCE AND IMPACT OF THE STUDY: In the event of a bioterror incident, e.g. deliberate release of Bacillus anthracis spores, areas require sampling to determine the magnitude and extent of contamination, and to establish decontamination efficacy. In this study, we investigate robotic sampling methods against high concentrations of bacterial spores applied by wet deposition to different floorings, contamination spread to other areas, potential transfer of spores to the operators and assessment of a wet vacuum robot for spore inactivation. The robots' usability was evaluated and how they can be employed in real life scenarios. This will help to reduce the economic cost of sampling and the risk to sampling/decontamination teams.

Is there an infection risk when playing drums contaminated with Bacillus anthracis?

AIMS: This study aims to investigate the aerosol release of a Bacillus anthracis spore surrogate from two different types of drums while playing, by; (i) quantifying the number of spores aerosolized during playing; (ii) investigating spore recovery from drums over long time periods, and (iii) measuring differences between (i) and (ii) for two different drums types. METHODS AND RESULTS: Two African drums were contaminated with Bacillus atrophaeus spores then sampled and played by hand over a number of days. During playing three air samplers were used to collect any aerosols generated, the choice of air samplers (Casella slit sampler, all glass impinger and six-stage Andersen sampler) allowed for characterization of the aerosols produced. CONCLUSIONS: Spore contamination of drums was found to be long-lasting with a small percentage of the spores being detached and aerosolized during drumming. The results of these studies have been used for a quantitative risk assessment of playing drums contaminated with B. anthracis spores. SIGNIFICANCE AND IMPACT OF THE STUDY: This demonstrates that the risk of inhalational exposure while playing drums contaminated with the levels linked to the US and UK cases is very low and that the resulting cases of inhalational anthrax can be explained by being unusual events involving highly susceptible persons.

Responding to biological incidents--what are the current issues in remediation of the contaminated environment?

Since 2000 there have been a number of biological incidents resulting in environmental contamination with Bacillus anthracis, the causative agent of anthrax. These incidents include the US anthrax attacks in 2001, the US and UK drumming incidents in 2006-2008 and more recently, anthrax contamination of heroin in 2009/2010 and 2012/2013. Remediation techniques used to return environments to normal have varied between incidents, with different decontamination technologies being employed. Many factors need to be considered before a remediation strategy or recovery option can be implemented, including; cost, time (length of application), public perception of risk, and sampling strategies (and results) to name a few. These incidents have demonstrated that consolidated guidance for remediating biologically contaminated environments in the aftermath of a biological incident was required. The UK Recovery Handbook for Biological Incidents (UKRHBI) is a project led by Public Health England (PHE), formerly the Health Protection Agency (HPA) to provide guidance and advice on how to remediate the environment following a biological incident or outbreak of infection, and is expected to be published in 2015.

Low-temperature decontamination with hydrogen peroxide or chlorine dioxide for space applications.

The currently used microbial decontamination method for spacecraft and components uses dry-heat microbial reduction at temperatures of >110°C for extended periods to prevent the contamination of extraplanetary destinations. This process is effective and reproducible, but it is also long and costly and precludes the use of heat-labile materials. The need for an alternative to dry-heat microbial reduction has been identified by space agencies. Investigations assessing the biological efficacy of two gaseous decontamination technologies, vapor hydrogen peroxide (Steris) and chlorine dioxide (ClorDiSys), were undertaken in a 20-m(3) exposure chamber. Five spore-forming Bacillus spp. were exposed on stainless steel coupons to vaporized hydrogen peroxide and chlorine dioxide gas. Exposure for 20 min to vapor hydrogen peroxide resulted in 6- and 5-log reductions in the recovery of Bacillus atrophaeus and Geobacillus stearothermophilus, respectively. However, in comparison, chlorine dioxide required an exposure period of 60 min to reduce both B. atrophaeus and G. stearothermophilus by 5 logs. Of the three other Bacillus spp. tested, Bacillus thuringiensis proved the most resistant to hydrogen peroxide and chlorine dioxide with D values of 175.4 s and 6.6 h, respectively. Both low-temperature decontamination technologies proved effective at reducing the Bacillus spp. tested within the exposure ranges by over 5 logs, with the exception of B. thuringiensis, which was more resistant to both technologies. These results indicate that a review of the indicator organism choice and loading could provide a more appropriate and realistic challenge for the sterilization procedures used in the space industry.

Meticillin-resistant Staphylococcus aureus is more resistant to vaporized hydrogen peroxide than commercial Geobacillus stearothermophilus biological indicators.

BACKGROUND: Vaporized hydrogen peroxide (VHP) is increasingly used in the decontamination of hospital isolation rooms. Commercially available bioindicators, most frequently Geobacillus stearothermophilus spores, are used to assess the efficacy of the decontamination phase. Staphylococcus aureus, including meticillin-resistant S. aureus (MRSA), produce catalase, which breaks down VHP, therefore potentially making it resistant to the decontamination phase. AIM: This investigation was designed to assess the resistance of meticillin-resistant S. aureus to VHP in comparison with commercially available biological indicators loaded with spores. METHODS: Stainless steel indicators were prepared with the same loading of MRSA (NCTC 13142) as commercially available indicators of G. stearothermophilus (ATCC 7953) (∼3.1×10(6) spores) and both indicators were exposed to a vapour hydrogen peroxide cycle (750 ppm). At set time-points during the exposure period, indicators containing both organisms were removed for processing and enumeration to compare survivability. FINDINGS: During the exposure period the recovery of MRSA from the coupons was between 1.5 and 3.5 log(10) higher than the recovery of G. stearothermophilus spores (P<0.05). This greater resistance may be due to the production of catalase which could break down the hydrogen peroxide, resulting in a reduction of the effectiveness of VHP. CONCLUSION: These findings highlight that the reduction achieved with a commercially available biological indicator cannot always be extrapolated to other micro-organisms. It must be recognized that although gaseous decontamination is the final step of the decontamination process, pre-cleaning of surfaces must be carried out to reduce the microbial loading being exposed.

Gaseous and air decontamination technologies for Clostridium difficile in the healthcare environment.

The recent data for hospital-acquired infections suggest that infection rates for meticillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile are beginning to decrease. However, while there is still pressure to maintain this trend, the resistance of C. difficile spores to standard detergents continues to present a problem for many UK hospitals trying to prevent its spread or control outbreaks. Alternative disinfection technologies such as gaseous decontamination are currently being marketed to the healthcare sector as an alternative/supplement to manual disinfection, and have been shown to be effective in reducing environmental contamination. When used correctly, they offer a complementary technology to manual cleaning that increases the probability of an effective reduction in viability and provides a comparatively uniform distribution of disinfectant. Three gaseous decontamination technologies are examined for their suitability in reducing environmental contamination with C. difficile: gaseous hydrogen peroxide, chlorine dioxide and ozone. Air decontamination and UV-based technologies are also briefly described. We conclude that while there is a role to play for these new technologies in the decontamination of ward surfaces contaminated with C. difficile, the requirement for both a preclean before use and the limited 'in vivo' evidence means that extensive field trials are necessary to determine their cost-effectiveness in a healthcare setting.

Evaluation of hydrogen peroxide gaseous disinfection systems to decontaminate viruses.

This study assessed the efficacy of two commonly used gaseous disinfection systems against high concentrations of a resistant viral surrogate in the presence and absence of soiling. MS2 bacteriophage suspensions were dried on to stainless steel carriers and exposed to hydrogen peroxide vapour (HPV) and vapour hydrogen peroxide (VHP) gaseous disinfection systems. The bacteriophages were also suspended and dried in 10% and 50% of horse blood to simulate the virus being present in a spill of blood/bodily fluids in a hospital ward environment. Carriers were removed from the gaseous disinfectant at regular intervals into phosphate-buffered saline, vortexed and assayed using a standard plaque assay. The effectiveness of both the HPV and VHP systems varied with the concentration of the bacteriophage with HPV resulting in a 6log(10) reduction in 10 min at the lowest viral concentration [10(7) plaque-forming units (pfu)/carrier] and requiring 45 min at the highest concentration (10(9) pfu/carrier). For the VHP system a 30 min exposure period was required to achieve a 6log(10) reduction at the lowest concentration and 60-90 min for the highest concentration. The addition of blood to the suspension greatly reduced the effectiveness of both disinfectants. This study demonstrates that the effectiveness of gaseous disinfectants against bacteriophage is a function of the viral concentration as well as the degree of soiling. It highlights the importance of effective cleaning prior to gaseous disinfection especially where high concentration agents are suspended in body fluids to ensure effective decontamination in hospitals.