Role of the Microbial Burden in the Acquisition and Control of Healthcare Associated Infections: The Utility of Solid Copper Surfaces - Use of Biocidal Surfaces for Reduction of Healthcare Acquired Infections - page 70

concentration of electromagnetic energy in the ultraviolet spectrum or by the
real-time distribution of reactive oxygen species, such as hydrogen peroxide,
singlet oxygen, hydroxyl radical or oxyanions. In general both systems have been
found to effectively reduce the concentration of microbes by at least 4 logs 10
[ 34 ]. Both systems have their limitations (See Chap. 9 ). Each requires skilled
labor to place the equipment and commence the disinfection cycle in the location
subjected to disinfection.
The disinfection reach of ultraviolet light is subject to the effects of shadowing
and 'cornering'. This typically requires that the equipment be placed in the center of
the room to insure uninform distribution of the lethal ultraviolet energy. Addition-
ally, the room must be vacant and any associated ultraviolet energy need be
prevented from leaking into areas occupied by people as the ultraviolet
(UV) light energy can damage eyesight and result in skin burns. The energy can
also shorten the life of equipment in the room as routine exposure to UV light can
accelerate decay by increasing the brittleness of many of the plastics used in the
fabrication of healthcare associated equipment.
The use of an automated UV-C light emitting system for the inactivation of
VRE, C. difficile and species of Acinetobacter has been found to be effective in
debulking the built environment of these pathogens. In one study, employing an
automated emitter in two hospitals, the concentrations of bacteria were reduced for
all 9 of the environmental sites tested and occurred regardless of whether the
sampled location was in direct or indirect line of sight of the UV source [ 3 ]. Further,
the extent of the reduction to the microbial burden was found to be significant for
VRE and C. difficile but not Acinetobacter spp. [ 3 ]. However, the data were
sufficiently compelling to lead the authors to conclude that the use of an automated
UV-C no-touch disinfection device can lead to a decrease in the bioburden of
important nosocomial pathogens in 'real-world' active clinical environments [ 3 ].
Another multi-hospital intervention used a pulsed xenon based UV delivery mech-
anism in concert with screening and hand hygiene education, together, the three were
able to significantly reduce (56 %, p

0.001) the incidence of hospital associated
MRSA infections in the study population [ 82 ]. Given that this was a bundled inter-
vention the contribution of the individual components of the bundle cannot be
discerned. However, the data do reinforce the common belief that any effective
infection control program requires a systematic approach in order to be effective.
As early as 1990 vapor phase hydrogen peroxide (HPV) has been advocated as an
effective surface decontaminant and sterilant [ 40 ]. In the intervening years a number
of devices have been developed to deploy this disinfectant/sterilant as a vapor into the
built clinical environment. In one study conducted by Passaretti and others, an
evaluation of the environmental and clinical impact of this no-touch technology was
assessed [ 59 ]. In a 30 month prospective cohort intervention trial involving 6 high risk
units from a 994 bed tertiary care hospital, they learned that patients admitted to rooms
decontaminated using HPV were 64 % less likely (p

¼

0.001) to acquire any multi-
drug resistant microbe and 80 % less likely to acquire VRE (p

<

0.001) after adjusting
for other factors [ 59 ]. Again, the complexity inherent to the transmission and
distribution of microbes within the built environment, coupled with the stochastic
nature of care, well illustrates that the risk of acquiring C. difficile , MRSA, and

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