Cycle times for hydrogen peroxide vapour decontamination

Abstract

We read with interest the research by Moat et al. investigating the in vitro efficacy of an ozone generator (Moat et al. 2009). In the discussion, the authors refer to the 2004 paper by French et al. investigating the efficacy of condensing hydrogen peroxide vapour (HPV) against methicillinresistant Staphylococcus aureus (French et al. 2004), stating, ‘‘Equivalent studies examining decontamination of hospital rooms with vaporized hydrogen peroxide have reported process times of 5 h.’’ Whilst this was the case in 2004, the introduction of improved aeration equipment to accelerate the catalytic conversion of HPV to oxygen and water vapour means that the cycle time for HPV decontamination is currently approximately 2 h. This is evidenced by several recent studies. For example, a study by Otter et al. investigated the feasibility of routine use of HPV decontamination in a US hospital from January 2006 to October 2007 (Otter et al. 2009). The median cycle time for the 1567 decontaminated rooms was 2 h 20 min. Similarly, in the United Kingdom, HPV technology was introduced into 7 National Health Service hospitals as part of the UK Department of Health funded Showcase Hospitals Project, to assess the feasibility of technologies that are proven to reduce healthcare-associated infections (Department of Health and NHS Purchasing and Supply Agency 2009). A recent conference paper using data from this project reported that the mean cycle time for single rooms was 1 h 40 min (Yezli et al. 2009). The difference between cycle times in the United Kingdom and United States relates to power constraints in the United States, meaning that injection is slower and the aeration equipment runs at a lower capacity. Both the US and UK studies conducted an assessment of room turnaround time, which includes time to clean the room before the cycle and to prepare the room for the next occupant after the cycle. Some level of precycle cleaning is necessary for all vapour-phase decontamination methods, including ozone, to remove visible soiling, which is not permissible for the next occupant, and gross levels of organic matter, which reduce the efficacy of disinfection. The median turnaround time from the vacation of the room to availability for occupation was 4 h in the study from the United States and 6 log10 reduction on a range of nosocomial pathogens, including Clostridium difficile, Acinetobacter baumannii, methicillin-resistant S. aureus, and vancomycin-resistant enterococci. In addition, routine use of HPV has been associated with a significant reduction in the incidence of C. difficile (Boyce 2009; Otter et al. 2009). Further studies are required to investigate the comparative efficacy of vapour-phase technologies, whether ozone generators are able to significantly reduce contamination in the busy healthcare setting, and whether any reductions effected are sufficient to reduce transmission (Boyce 2009).