How effective are UV or misting technologies?

Chemical fumigation was used in the 1960s to supplement standard environmental surface disinfection in hospital isolation rooms (1). As mentioned in my last blog, the CDC in their Guidelines for Environmental Infection Control in Health-Care Facilities, recommend against using chemical fogging due to the lack of evidence that it is an efficacious technology for disinfection (2). However, because of the success in 2001 in destroying anthrax bacteria and their spores in the heavily contaminated Hart Senate Office Building and some U.S. Post Office facilities by using fumigation (3), hospitals have begun adopting fumigation techniques, as well as UV as an adjunct to routine cleaning methods. In my previous blog I generally discussed the biocidal mode of action and the pros and cons of using UV irradiation or hydrogen peroxide fumigation (HPV) in the hospital environment. In the current blog, I would like to briefly review and discuss the studies that assessed the effectiveness of these technologies in killing microorganisms and more specifically the clinical trials examining if indeed these no-touch technologies are effective in reducing HAI.

In general, it has been demonstrated that epidemiologic important health care–associated pathogens bioburden, such as of MRSA, VRE, Acinetobacter spp, and different viruses, either experimentally spiked or in actual contaminated rooms, can be significantly reduced by UV or HPV and that greater time, energy and cycles are required to kill spore-forming organisms, such as C. difficile (4). So, have these technologies been demonstrated to reduce HAI?

This was recently very thoroughly reviewed by Weber et al (4).Briefly, at least 10 trials have assessed the capacity of the UV and HPV no touch systems to reduce HAI. Four out of the 5 HPV related trials, and 4 out of the 5 UV related trials, demonstrated a statistical significant reduction of at least one type of HAI. For example, a 30-month before-after study in 6 high-risk units found that patients admitted to rooms decontaminated using HPV were 64% less likely to acquire any multidrug-resistant pathogen (P < .001) and 80% less likely to acquire VRE (P < .001) (5). However, several of these studies had some limitations, e.g. no monitoring of hand compliance was performed or other HAI prevention initiatives were included,

Overall these studies indicate that HPV and UV irradiation contribute to environmental cleaning and terminal room disinfection and their use may help reduce HAI. Nevertheless, further more rigorous studies, such as randomized cross-over studies with multiple sites or multiple cross-over points should be performed in order to minimize potential biases such as in before and after studies. A recent example of such a rigorous study is a cluster-randomised clinical trial that demonstrated that UV-C decontamination of rooms previously occupied by patients colonized or infected with MRSA, VRE, or with C. difficile decreased by approximately 10%-30% (P = .036) the acquisition of the above mentioned organisms by subsequent patients admitted to these rooms (6).

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