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Centre for Clinical Infection and Diagnostics Research (CIDR), Department of Infectious Diseases, King's College London, School of Medicine and Guy's and St Thomas' NHS Foundation Trust, UKBioquell UK Ltd, Andover, Hampshire, UK
Division of Infectious Diseases, Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD, USADepartment of Hospital Epidemiology and Infection Control, The Johns Hopkins Hospital, Baltimore, MD, USA
Centre for Clinical Infection and Diagnostics Research (CIDR), Department of Infectious Diseases, King's College London, School of Medicine and Guy's and St Thomas' NHS Foundation Trust, UK
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 (H2O2) 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.
Role of hospital surfaces in the transmission of emerging health care-associated pathogens: norovirus, Clostridium difficile, and Acinetobacter species.
Recent studies show that admission to a room previously occupied by a patient with Clostridium difficile, vancomycin-resistant enterococci (VRE), meticillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii and Pseudomonas aeruginosa increases the risk of acquiring these pathogens for subsequent occupants of the same room by a factor of two or more.
In these circumstances, current terminal cleaning and disinfection following the discharge of patients with these pathogens is inadequate and needs to be improved. The emergence of the 027/NAP1 epidemic strain of C. difficile and potentially untreatable multidrug-resistant Gram-negative bacteria that can also survive on surfaces is a further reason to improve environmental decontamination.
Effective cleaning and disinfection using conventional methods relies on a human operator to correctly select and formulate an appropriate agent and distribute the agent to all target surfaces for the necessary contact time. Improvement of these conventional methods depends on modification of human behaviour, which is often difficult. The use of novel ‘no-touch’ automated room disinfection (NTD) systems provides an alternative approach, which removes or reduces reliance on the operator.
Automated systems have been adopted widely in other areas of healthcare to remove human error. Examples include robotic surgery and many aspects of critical care such as ventilators. Indeed, commenting on the future of infection control in the late 1990s, Dr Robert Weinstein wrote: ‘Given the choice of improving technology or improving human behavior, technology is the better choice.
Despite the relatively recent attention, the concept of NTD is not new. A paper was published in 1901 advising on how to disinfect a ‘sick-room’ through gaseous formaldehyde.
However, advice from the US Centers for Disease Control and Prevention (CDC) since the 1970s is that disinfectant fogging should not be performed routinely in patient-care areas.
Rutala WA, Weber DJ, Healthcare Infection Control Practices Advisory Committee (HICPAC). Guideline for disinfection and sterilization in healthcare facilities. 2008.
The emergence of several new NTD systems based on either H2O2 or ultraviolet (UV) radiation and the increasing recognition of the importance of environmental contamination in transmission suggests that this recommendation should be re-evaluated.
This review presents evidence for the need to improve or augment conventional cleaning and disinfection; considers the targets for hospital disinfection and when use of an NTD system may be appropriate; summarizes and compares evidence relating to the various NTD systems; and discusses the role of regulators and professional societies in guiding evidence-based adoption.
What level of surface contamination is a risk for transmission?
The relationship between the level of residual surface contamination after disinfection and the risk of transmission has not been studied in detail. It depends on various factors, including the characteristics of the organism involved, patient susceptibility and staff compliance with infection control policies (for example hand hygiene following contact with environmental surfaces).
Risk of hand or glove contamination after contact with patients colonized with vancomycin-resistant Enterococcus or the colonized patients' environment.
Contamination of hands with methicillin-resistant Staphylococcus aureus after contact with environmental surfaces and after contact with the skin of colonized patients.
The fact that subsequent occupants of a room vacated by a previously colonized or infected patient are at an increased risk of infection indicates that conventional terminal disinfection does not reduce contamination sufficiently to prevent all transmission in these cases.
There is some evidence that the extent to which transmission is interrupted is proportional to the level of surface contamination. For example, Lawley et al. used an in vitro mouse model to show that the degree to which transmission of C. difficile was blocked correlated with the log10 reduction of the various disinfectants tested.
The degree of shedding and the infective dose can be used to guide the appropriate target for hospital cleaning and disinfection. Certain pathogens such as C. difficile and norovirus can be shed into the environment in high numbers and have a low infectious dose.
For example, stool concentrations of norovirus can reach >1 × 1012 particles per gram and up to 105 virus norovirus particles per 30 cm2 have been identified on hospital surfaces, whereas the infectious dose is 1–100 particles.
Therefore, the presence of a pathogen on a surface at any concentration may be a risk for transmission. This is reflected in proposed guidelines for microbiological hygiene standards and recent discussion surrounding the intended target for hospital disinfection.
However, in practice, a risk-based approach must be used when setting a target for an acceptable level of residual contamination, balancing patient safety with practicality and cost, as is the case when selecting liquid disinfectants. More stringent targets should be set when the risk and/or consequences of infection are high, for example, for virulent, resistant and/or highly infectious pathogens, especially in high-risk settings with immunocompromised patients; a lower standard may be acceptable in lower-risk settings.
Limitations of conventional cleaning and disinfection
Conventional cleaning and disinfection is performed by a human operator with liquid detergents or disinfectants. Microbiological studies indicate that conventional cleaning and disinfection without programmes of targeted improvement rarely eradicate pathogens from surfaces.
Tackling contamination of the hospital environment by methicillin-resistant Staphylococcus aureus (MRSA): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination.
Isolation of Acinetobacter baumannii complex and methicillin-resistant Staphylococcus aureus from hospital rooms following terminal cleaning and disinfection: can we do better?.
Problems associated with both ‘product’ and ‘procedure’ contribute to this (Box 1), in particular, the reliance on the operator to repeatedly ensure adequate selection, formulation, distribution and contact time of the agent. For example, a large assessment of conventional cleaning in 36 acute hospitals using fluorescent markers revealed that less than 50% of high-risk objects in hospital rooms were cleaned at patient discharge.
Modifying human behaviour is difficult but several different approaches can be taken, including routine microbiological analysis of surface hygiene, the use of fluorescent markers or ATP assays to assess the thoroughness of cleaning, feedback of cleaning performance and educational campaigns.
Monitoring and feedback can improve the frequency of surfaces that are cleaned and reduce the level of environmental contamination and there is some evidence that improving the efficacy of conventional cleaning/disinfection can reduce the acquisition of pathogens.
Impact of an environmental cleaning intervention on the presence of methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci on surfaces in intensive care unit rooms.
Reduction of Clostridium difficile and vancomycin-resistant Enterococcus contamination of environmental surfaces after an intervention to improve cleaning methods.
However, no studies have evaluated the sustainability of such systematic improvements. Indeed, recent evidence indicates that altering the location of fluorescent dye spots reduced the proportion of objects that were cleaned from 90% to approximately 60%.
In situations where the elimination of pathogens is required, even systematic improvement of conventional cleaning and disinfection may not be sufficient. Multiple rounds of disinfection with sodium hypochlorite (bleach) taking many hours, risking damage to materials and presenting health risks for operators may have limited success in removing environmental reservoirs of pathogens.
Isolation of Acinetobacter baumannii complex and methicillin-resistant Staphylococcus aureus from hospital rooms following terminal cleaning and disinfection: can we do better?.
Notwithstanding current CDC guidelines recommending against routine ‘disinfectant fogging’ in patient-care areas, the use of an NTD system may be warranted in some circumstances based on current data.
Rutala WA, Weber DJ, Healthcare Infection Control Practices Advisory Committee (HICPAC). Guideline for disinfection and sterilization in healthcare facilities. 2008.
Figure 1 outlines a hierarchical approach to hospital disinfection, identifying areas where NTD systems may be appropriate, and Table I highlights specific scenarios where various NTD systems may be considered. The strongest reason for considering an NTD system is to prevent environment-borne transmission by improving terminal disinfection of clinical areas after infected or colonized patients have been discharged (Figure 1).
Kaiser M, Elemendorf S, Kent D, Evans A, Harrington SM, McKenna D. Management of a multi-year MDR Acinetobacter baumannii outbreak in the ICU setting. Infectious Diseases Society of America (IDSA) Annual Meeting. Abstract 394. 2011.
Hydrogen peroxide vapor decontamination of an intensive care unit to remove environmental reservoirs of multidrug-resistant gram-negative rods during an outbreak.
Use of vaporized hydrogen peroxide decontamination during an outbreak of multidrug-resistant Acinetobacter baumannii infection at a long-term acute care hospital.
Hydrogen peroxide vapor decontamination of an intensive care unit to remove environmental reservoirs of multidrug-resistant gram-negative rods during an outbreak.
Figure 1Proposed approach for a disinfection decision diagram. aKey pathogens associated with contamination of the environment include C. difficile, vancomycin-resistant enterococcus, meticillin-resistant S. aureus, A. baumannii, P. aeruginosa and norovirus. bFor detailed scenarios when a ‘no-touch’ automated room disinfection (NTD) system may be considered (Table I). All NTD systems are applied after a cleaning step to ensure that surfaces are free from visible contamination, which is unacceptable to subsequent patients and will reduce the efficacy of the NTD disinfection. cThere is limited equivocal evidence that enhanced cleaning/disinfection in a low-risk general ward setting can reduce the spread of pathogens.
Table IDetailed scenarios for when to consider a ‘no-touch’ automated room disinfection (NTD) system for terminal disinfection of clinical areas used by patients infected or colonized with pathogens associated with transmission from the environment
The risk associated with individual pathogens in the context of disinfection will depend on a number of factors, including the importance of environmental contamination in transmission, clinical implications, local epidemiology and financial outcomes. For example, a multidrug-resistant Gram-negative rod causing an outbreak would be considered a ‘high-risk’ pathogen, whereas VRE colonization would be considered lower risk.
High-risk environmental–pathogenic characteristics (e.g. C. difficile)
The risk associated with individual pathogens in the context of disinfection will depend on a number of factors, including the importance of environmental contamination in transmission, clinical implications, local epidemiology and financial outcomes. For example, a multidrug-resistant Gram-negative rod causing an outbreak would be considered a ‘high-risk’ pathogen, whereas VRE colonization would be considered lower risk.
A cleaning step to ensure that surfaces are free from visible contamination is required before all NTD systems to make the area aesthetically acceptable to the next occupant, and increase the efficacy of NTD disinfection.
Tackling contamination of the hospital environment by methicillin-resistant Staphylococcus aureus (MRSA): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination.
Reduction of Clostridium difficile and vancomycin-resistant Enterococcus contamination of environmental surfaces after an intervention to improve cleaning methods.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
Reduction of Clostridium difficile and vancomycin-resistant Enterococcus contamination of environmental surfaces after an intervention to improve cleaning methods.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
Impact of an environmental cleaning intervention on the presence of methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci on surfaces in intensive care unit rooms.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
Tackling contamination of the hospital environment by methicillin-resistant Staphylococcus aureus (MRSA): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination.
Isolation of Acinetobacter baumannii complex and methicillin-resistant Staphylococcus aureus from hospital rooms following terminal cleaning and disinfection: can we do better?.
Isolation of Acinetobacter baumannii complex and methicillin-resistant Staphylococcus aureus from hospital rooms following terminal cleaning and disinfection: can we do better?.
Isolation of Acinetobacter baumannii complex and methicillin-resistant Staphylococcus aureus from hospital rooms following terminal cleaning and disinfection: can we do better?.
Tackling contamination of the hospital environment by methicillin-resistant Staphylococcus aureus (MRSA): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination.
Impact of an environmental cleaning intervention on the presence of methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci on surfaces in intensive care unit rooms.
Isolation of Acinetobacter baumannii complex and methicillin-resistant Staphylococcus aureus from hospital rooms following terminal cleaning and disinfection: can we do better?.
Hydrogen peroxide vapor decontamination of an intensive care unit to remove environmental reservoirs of multidrug-resistant gram-negative rods during an outbreak.
ICU, intensive care unit; VRE, vancomycin-resistant enterococcus; MRSA, meticillin-resistant Staphylococcus aureus; UVC, ultraviolet C spectrum; aHP, aerosolized hydrogen peroxide.
‘Yes’, method is appropriate based on current data; ‘No’, method is inappropriate based on current data.
a The risk associated with individual pathogens in the context of disinfection will depend on a number of factors, including the importance of environmental contamination in transmission, clinical implications, local epidemiology and financial outcomes. For example, a multidrug-resistant Gram-negative rod causing an outbreak would be considered a ‘high-risk’ pathogen, whereas VRE colonization would be considered lower risk.
b A cleaning step to ensure that surfaces are free from visible contamination is required before all NTD systems to make the area aesthetically acceptable to the next occupant, and increase the efficacy of NTD disinfection.
c The use of an NTD system to disinfect multi-occupancy areas may not be warranted in a low-risk setting due to the requirement to block beds.
Conversely, NTD systems are not suitable for performing daily disinfection before patients are discharged due to the need for temporary relocation of the patient. Thus, concerns about recontamination by the room occupant after the NTD intervention are not well placed when considering terminal disinfection because although this recontamination may lead to some indirect infection, it does not prevent the chain of infection between consecutive occupants of the same room being broken.
Risk of hand or glove contamination after contact with patients colonized with vancomycin-resistant Enterococcus or the colonized patients' environment.
Tackling contamination of the hospital environment by methicillin-resistant Staphylococcus aureus (MRSA): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination.
Asymptomatic carriers are a potential source for transmission of epidemic and nonepidemic Clostridium difficile strains among long-term care facility residents.
Other potential applications of NTD systems include the removal of environmental pathogens disturbed during building works such as Aspergillus fumigatus, as part of emergency preparedness planning, the disinfection of mobile medical equipment in a dedicated facility, and decontamination of emergency vehicles or operating theatres.
Due to the potential for mobile medical equipment, such as blood pressure cuffs and mobile computers to become contaminated, combined with the challenge of disinfecting them effectively, the feasibility and effectiveness of NTD systems for disinfecting these items should be prioritized for evaluation.
What is on that keyboard? Detecting hidden environmental reservoirs of Clostridium difficile during an outbreak associated with North American pulsed-field gel electrophoresis type 1 strains.
Several different types of NTD system are currently used in clinical healthcare settings, the most common being aerosolized hydrogen peroxide (aHP) systems (such as ASP Glosair, previously Sterinis, Steris Biogienie and Oxypharm Nocospray), H2O2 vapour systems (such as the Bioquell and Steris systems), and ultraviolet C radiation (UVC) systems (such as Lumalier Tru-D).
The different characteristics of these three system types are summarized in Table II. A fourth class of NTD system based on pulsed-xenon UV (PX-UV) radiation has emerged relatively recently and with a limited literature so far.
Use of vaporized hydrogen peroxide decontamination during an outbreak of multidrug-resistant Acinetobacter baumannii infection at a long-term acute care hospital.
Use of vaporized hydrogen peroxide decontamination during an outbreak of multidrug-resistant Acinetobacter baumannii infection at a long-term acute care hospital.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
Use of vaporized hydrogen peroxide decontamination during an outbreak of multidrug-resistant Acinetobacter baumannii infection at a long-term acute care hospital.
Tackling contamination of the hospital environment by methicillin-resistant Staphylococcus aureus (MRSA): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination.
Comparison of the efficacy of a hydrogen peroxide dry-mist disinfection system and sodium hypochlorite solution for eradication of Clostridium difficile spores.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
Efficacy of dry mist of hydrogen peroxide (DMHP) against Mycobacterium tuberculosis and use of DMHP for routine decontamination of biosafety level 3 laboratories.
3: ‘A potentially useful new concept but insufficiently validated; more research and development is required before it is ready for evaluation in practice.’
1: ‘Basic research and development, validation and recent in-use evaluations have shown benefits that should be available to NHS bodies to include as appropriate in their cleaning, hygiene or infection control protocols.’ (HPV)
None
EPA registration
Unknown
Sterilant
Unknown
Evidence of clinical impact
None published
Significant reduction in the incidence of C. difficile and VRE. (HPV)
Manian FA, Griesenauer S, Senkel D. Impact of an intensive terminal cleaning and disinfection (C/D) protocol involving selected hospital rooms on endemic nosocomial infection (NI) rates of common pathogens at a tertiary care medical center. 5th Decennial Meeting of the Society for Healthcare Epidemiology of America (SHEA), Atlanta, GA, USA. Abstract LB6. 2010.
An evaluation of environmental decontamination with hydrogen peroxide vapor for reducing the risk of patient acquisition of multidrug-resistant organisms.
Clin Infect Dis.2012 Oct 5; ([Epub ahead of print])
Hydrogen peroxide vapor decontamination of an intensive care unit to remove environmental reservoirs of multidrug-resistant gram-negative rods during an outbreak.
Otter JA, Davies B, Klein J, Watts TL, Kearns AM, French GL. Identification and control of an outbreak of gentamicin-resistant, methicillin-susceptible Staphylococcus aureus on a neonatal unit. 13th International Symposium on Staphylococci and Staphylococcal Infection (ISSSI), Cairns, Australia, 2008.
Aerosolized H2O2 systems deliver a pressure-generated aerosol. The systems employed most frequently in healthcare use a solution containing 5–6% H2O2 and <50 ppm silver.
One manufacturer (ASP Glosair) states a particle size of 8–10 μm whereas another manufacturer (Oxypharm Nocospray) states a smaller particle size of 0.5 μm.
Comparison of the efficacy of a hydrogen peroxide dry-mist disinfection system and sodium hypochlorite solution for eradication of Clostridium difficile spores.
However, aHP systems have not been shown to eradicate pathogens in clinical practice. For example, one or more positive C. difficile culture was collected from 20% of 15 and 50% of 10 rooms studied after an aHP process.
Comparison of the efficacy of a hydrogen peroxide dry-mist disinfection system and sodium hypochlorite solution for eradication of Clostridium difficile spores.
One aHP system (ASP Glosair) achieves an ∼4-log10 reduction on C. difficile spores in vitro and has limited capacity to inactivate commercially produced 6-log10 spore biological indicators (BIs).
Comparison of the efficacy of a hydrogen peroxide dry-mist disinfection system and sodium hypochlorite solution for eradication of Clostridium difficile spores.
The efficacy of aHP systems against catalase-positive bacteria remains to be firmly established, with conflicting published data on the level of inactivation of MRSA and A. baumannii and the tuberculocidal activity of aHP.
Activity of a dry mist-generated hydrogen peroxide disinfection system against methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii.
Efficacy of dry mist of hydrogen peroxide (DMHP) against Mycobacterium tuberculosis and use of DMHP for routine decontamination of biosafety level 3 laboratories.
This is likely because catalase-positive bacteria are considerably less susceptible to the 5–6% H2O2 aerosol used by aHP systems than catalase-negative bacteria or metabolically inert spores.
Meticillin-resistant Staphylococcus aureus is more resistant to vaporized hydrogen peroxide than commercial Geobacillus stearothermophilus biological indicators.
There is no published evidence that disinfection with aHP systems reduces epidemic or endemic infection rates.
Practical considerations
Aerosolized H2O2 is straightforward to use compared with H2O2 vapour systems and relatively inexpensive compared with H2O2 vapour and UVC systems. The capacity of single units to decontaminate areas larger than single rooms is limited, so multiple generators may be necessary.
Doors and air vents should be sealed and hand-held health and safety monitors are required to ensure that no leakage occurs during cycles and to verify that the concentration of H2O2 inside the enclosure is below health and safety exposure limits before permitting patients or staff to enter the room.
However, cycle times for single rooms may be considerably longer when hand-held sensors are used to ensure that H2O2 concentrations are below health and safety limits prior to room re-entry.
Some studies suggest that homogeneous distribution of the active agent is not achieved, perhaps because aHP is introduced via a unidirectional nozzle and the particles are affected by gravity, thus being more effective on lower horizontal surfaces.
Data are awaited confirming the compatibility of aHP systems with common hospital materials, including sensitive electronics. Finally, several studies have noted equipment reliability problems, which was a feature of older foggers.
H2O2 vapour systems deliver a heat-generated vapour of 30–35% w/w aqueous H2O2 through a high velocity air stream to achieve homogeneous distribution throughout an enclosed area (enclosure).
Two systems using H2O2 vapour are available commercially: Bioquell and Steris (Table II). Bioquell systems are usually termed hydrogen peroxide vapour (HPV) and Steris systems vaporized hydrogen peroxide (VHP). Bioquell HPV includes a generator to produce HPV, modules to measure the concentration of HPV, temperature and relative humidity in the enclosure and an aeration unit to catalyse the breakdown of HPV to oxygen and water vapour after HPV exposure. A control pedestal is situated outside the enclosure to provide remote control. Bioquell HPV is delivered until the air in the enclosure becomes saturated and H2O2 begins to condense on surfaces.
Use of vaporized hydrogen peroxide decontamination during an outbreak of multidrug-resistant Acinetobacter baumannii infection at a long-term acute care hospital.
Steris VHP systems have a generator inside the room with an integral aeration unit and dehumidifier required to achieve a set humidity level prior to the cycle commencement. The system is controlled remotely from outside the enclosure. Steris VHP systems deliver ‘non-condensing’ VHP by drying the vapour stream as it is returned to the generator. Bioquell systems do not control the H2O2 air concentration throughout the exposure period whereas the Steris systems hold a steady H2O2 air concentration throughout the exposure period.
Microbiological efficacy
Both Bioquell HPV and Steris VHP systems are US Environmental Protection Agency (EPA)-registered sterilants, which means that they have passed the AOAC sporicide test on porous and non-porous surfaces.
Both systems are associated with the eradication of pathogens from surfaces in situ and cycles are validated by >6-log10 reduction of Geobacillus stearothermophilus BI spores.
Isolation of Acinetobacter baumannii complex and methicillin-resistant Staphylococcus aureus from hospital rooms following terminal cleaning and disinfection: can we do better?.
Hydrogen peroxide vapor decontamination of an intensive care unit to remove environmental reservoirs of multidrug-resistant gram-negative rods during an outbreak.
Use of vaporized hydrogen peroxide decontamination during an outbreak of multidrug-resistant Acinetobacter baumannii infection at a long-term acute care hospital.
Otter JA, Davies B, Klein J, Watts TL, Kearns AM, French GL. Identification and control of an outbreak of gentamicin-resistant, methicillin-susceptible Staphylococcus aureus on a neonatal unit. 13th International Symposium on Staphylococci and Staphylococcal Infection (ISSSI), Cairns, Australia, 2008.
HPV and VHP are sporicidal, bactericidal, mycobactericidal and virucidal, achieving >6-log10 reduction against a wide range of nosocomial pathogens including C. difficile spores, MRSA, VRE, A. baumannii and norovirus surrogates, though efficacy may be reduced by high loading and the presence of organic soil.
Goyal SM, Chander Y, Yezli S, Otter JA. Hydrogen peroxide vapor (HPV) inactivation of feline calicivirus, a surrogate for norovirus – an update. Infection Prevention Society Annual Meeting. 2011.
HPV has been used to remove environmental reservoirs during outbreaks of C. difficile, MRSA and meticillin-susceptible S. aureus (MSSA), resistant Gram-negatives and other pathogens.
Kaiser M, Elemendorf S, Kent D, Evans A, Harrington SM, McKenna D. Management of a multi-year MDR Acinetobacter baumannii outbreak in the ICU setting. Infectious Diseases Society of America (IDSA) Annual Meeting. Abstract 394. 2011.
Hydrogen peroxide vapor decontamination of an intensive care unit to remove environmental reservoirs of multidrug-resistant gram-negative rods during an outbreak.
Otter JA, Davies B, Klein J, Watts TL, Kearns AM, French GL. Identification and control of an outbreak of gentamicin-resistant, methicillin-susceptible Staphylococcus aureus on a neonatal unit. 13th International Symposium on Staphylococci and Staphylococcal Infection (ISSSI), Cairns, Australia, 2008.
Use of vaporized hydrogen peroxide decontamination during an outbreak of multidrug-resistant Acinetobacter baumannii infection at a long-term acute care hospital.
Two pre–post and one cohort study have evaluated the clinical impact of HPV; there are no data for the clinical impact of VHP aside from outbreak settings.
Manian FA, Griesenauer S, Senkel D. Impact of an intensive terminal cleaning and disinfection (C/D) protocol involving selected hospital rooms on endemic nosocomial infection (NI) rates of common pathogens at a tertiary care medical center. 5th Decennial Meeting of the Society for Healthcare Epidemiology of America (SHEA), Atlanta, GA, USA. Abstract LB6. 2010.
An evaluation of environmental decontamination with hydrogen peroxide vapor for reducing the risk of patient acquisition of multidrug-resistant organisms.
Clin Infect Dis.2012 Oct 5; ([Epub ahead of print])
Boyce et al. performed a before–after study showing that HPV decontamination of rooms vacated by patients with C. difficile infection (CDI) significantly reduced the incidence of CDI on five focus wards and hospital-wide, when the analysis was restricted to the months when the epidemic strain was known to be present.
A conference abstract by Manian et al. showed that HPV decontamination of rooms vacated by patients with a range of pathogens significantly reduced the rate of C. difficile and VRE infection, and substantially reduced the rate of MRSA and multidrug-resistant A. baumannii infection.
Manian FA, Griesenauer S, Senkel D. Impact of an intensive terminal cleaning and disinfection (C/D) protocol involving selected hospital rooms on endemic nosocomial infection (NI) rates of common pathogens at a tertiary care medical center. 5th Decennial Meeting of the Society for Healthcare Epidemiology of America (SHEA), Atlanta, GA, USA. Abstract LB6. 2010.
A cohort study by Passaretti et al. found that patients admitted to rooms vacated by patients with multidrug-resistant organisms (MDROs) and disinfected using HPV were 64% less likely to acquire MDROs than patients admitted to rooms vacated by patients with MDROs and disinfected using standard methods.
An evaluation of environmental decontamination with hydrogen peroxide vapor for reducing the risk of patient acquisition of multidrug-resistant organisms.
Clin Infect Dis.2012 Oct 5; ([Epub ahead of print])
An evaluation of environmental decontamination with hydrogen peroxide vapor for reducing the risk of patient acquisition of multidrug-resistant organisms.
Clin Infect Dis.2012 Oct 5; ([Epub ahead of print])
Tackling contamination of the hospital environment by methicillin-resistant Staphylococcus aureus (MRSA): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination.
Hydrogen peroxide vapor decontamination of an intensive care unit to remove environmental reservoirs of multidrug-resistant gram-negative rods during an outbreak.
However, HPV is less straightforward than UVC and aHP systems because it requires two units (a generator and aeration unit) for a single room. Door and air vents need to be sealed. As with aHP, hand-held health and safety monitors are required to ensure that no leakage occurs during cycles and to verify that the concentration of H2O2 inside the enclosure is below health and safety exposure limits before permitting patients or staff to enter the room. Thus, staff training requirements for using H2O2 vapour systems are higher than for UV systems. The potential for selection of less susceptible strains is lower than for aHP or UV systems because the high-concentration H2O2 vapour systems typically eradicate pathogens so that few micro-organisms undergo sublethal exposure. Reported cycle times are currently 1.5–2.5 h for a single room for HPV and 8 h for VHP.
Use of vaporized hydrogen peroxide decontamination during an outbreak of multidrug-resistant Acinetobacter baumannii infection at a long-term acute care hospital.
Environmental Protection Agency (USA). Compatibility of material and electronic equipment with hydrogen peroxide and chlorine dioxide fumigation. Assessment and evaluation report. 2010.
UVC systems for room decontamination deliver specific doses (for example, 12,000 μWs/cm2 for vegetative bacteria and 22,000–36,000 μWs/cm2 for spores) of UVC (254 nm range) to surfaces.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
The device is placed in the centre of the room and frequently touched mobile items are arranged close to the device for optimal exposure. UVC travels in straight lines and is less effective out of direct line of sight from the device. Some manufacturers therefore recommend multiple cycles from different locations.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
It may be possible to improve efficacy at the cost of extending cycles. Importantly, the microbiological reduction is significantly lower out of direct line of sight of the device.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
For example, in one study of a UVC device, a 1-log10 reduction was achieved on C. difficile spores inoculated on plastic carriers placed 10 feet away from the device out of direct line of sight, compared with 2.6-log10 reduction in direct line of sight.
Evaluation of an automated ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens in hospital rooms.
Further clinical studies on this and other pathogens are needed to assess the potential role of UVC systems in reducing nosocomial infection rates.
Practical considerations
UVC is easy to use, does not require sealing of door or air vents and has a relatively short cycle time. Many high-touch sites may be out of line of sight; some manufacturers recommended multiple cycles in different parts of the room to overcome this problem but this places reliance on the operator to choose appropriate equipment locations, has implications for cycle times and requires more hands-on operator time. A recent study indicates that a UVC spore cycle in rooms ranging from 46 to 86 m3 took a median of 84 min (range: 72–146) for a two-stage procedure (where the UVC unit is positioned at two locations during the cycle) and median of 68 min (range: 34–100) for a one-stage procedure.
Since some UVC systems rely on measurement of reflected dose to determine the cycle, the presence of surfaces that do not reflect UVC, or reflect it inefficiently (such as glass), variations in temperature and humidity and the age of the bulbs will affect the reflected dose and may increase the cycle times.
The intensity of the UV light dissipates with the square of the distance from the source, which limits the capacity of UVC devices to disinfect areas larger than single patient rooms.
Assessment and characterization of degradation effect for the varied degrees of ultra-violet radiation onto the collagen-bonded polypropylene non-woven fabric surfaces.
Levin J, Parrish C, Riley L, English D. The use of portable pulsed xenon ultraviolet light (PPX-UV) after terminal cleaning was associated with a dramatic decrease in the hospital-associated Clostridium difficile infection (HA-CDI) rate in a community hospital. Infectious Diseases Society of America (IDSA) Annual Meeting. Abstract 342. 2011.
However, the study was performed for a short duration so further data are awaited.
Practical considerations
Pulsed-xenon ultraviolet systems have similar practical considerations to UVC systems, including the need to use multiple room locations to address line-of-sight issues, the age of the bulbs affecting intensity of the pulse, limited capacity to decontaminate areas larger than single rooms and the potential for mutagenesis. Also, the system operates using a series of bright ‘camera flashes’, which may be disruptive to patients. However, given the short cycles associated with PX-UV, it should be prioritized for further evaluation.
Other systems
Gaseous ozone can achieve a high level of microbial inactivation.
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