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| Dr. Bill Rutala |
There is excellent evidence in the
scientific literature that environmental contamination plays an important role
in the transmission of several key healthcare-associated pathogens including
methicillin-resistant Staphylococcus
aureus [MRSA] ,
vancomycin-resistant Enterococcus [VRE],
Acinetobacter, norovirus, and Clostridium difficile.1-4 All these pathogens have been demonstrated to
persist in the environment for hours to days (in some cases months)5, to frequently
contaminate the environmental surfaces in rooms of colonized or infected
patients, to transiently colonize the hands of healthcare personnel, to be
transmitted by healthcare personnel, and to cause outbreaks in which
environmental transmission was deemed to play a role. Further, admission to a room in which the
previous patient had been colonized or infected with MRSA, VRE, Acinetobacter or C. difficile, has been shown to be a risk factor for the newly
admitted patient to develop colonization or infection.6-8
It has long been recommended in the
United States that environmental surfaces in patient rooms be
cleaned/disinfected on a regular basis (e.g., daily, 3 times per week), when
surfaces are visibly soiled, and following patient discharge (terminal
cleaning).9 Studies have demonstrated that adequate
environment cleaning is frequently lacking.
For example, Carling and co-workers assessed the thoroughness of
terminal cleaning in the patient’s immediate environment in 23 acute care hospitals
(1,119 patient rooms) by using a transparent, easily cleaned, stable solution
that fluoresces when exposed to hand-held ultraviolet (UV) light.10 The overall thoroughness of cleaning,
expressed as a percent of surfaces evaluated, was 49% (range for all hospitals,
35%-81%). Further, while interventions
aimed at improving cleaning thoroughness have demonstrated effectiveness, many
surfaces remain inadequately cleaned and therefore potentially
contaminated. For this reason, several
manufacturers have developed room disinfection units that can decontaminate
environmental surfaces and objects. These
systems use one of two methods; either ultraviolent light or hydrogen peroxide.11,
12 These technologies supplement, but do not
replace, standard cleaning and disinfection because surfaces must be physically
cleaned of dirt and debris.
Additionally, these methods can only be used for terminal or discharge
room decontamination (i.e., cannot be used for daily room decontamination)
because the room must be emptied of people.
This article summarizes a recent publications of this topic. 13
Ultraviolet
Light for Room Decontamination
UV irradiation has
been used for the control of pathogenic microorganisms in a variety of applications,
such as control of legionellosis, as well as disinfection of air, surfaces, and
instruments.14,
15 At
certain wavelengths, UV light will break the molecular bonds in DNA, thereby
destroying the organism. UV-C has a
characteristic wavelength of 200-270 nm (e.g., 254 nm), which lies in the
germicidal active portion of the electromagnetic spectrum of 200-320 nm. The efficacy of UV irradiation is a function
of many different parameters such as intensity, exposure time, lamp placement,
and air movement patterns.
An automated mobile
UV-C unit (Tru-D, Lumalier Corporation) has been shown to eliminate >3-log10
vegetative bacteria (MRSA, VRE, Acinetobacter
baumannii) and >2.4-log10 C.
difficile seeded onto formica surfaces in patients’ rooms experimentally
contaminated.4 There are three studies that have
demonstrated that this UV-C system is capable of reducing vegetative bacteria
inoculated on a carrier by >3-4-log10 in 15-20 minutes and C. difficile by >1.7-4-log10
in 35-100 minutes.4,
16, 17 The studies demonstrate reduced effectiveness when
surfaces were not in direct line-of-sight.
Investigators have also demonstrated the effectives of an automated
ultraviolet-C emitter against VRE, MRSA, Acinetobacter
spp and C. difficile in patient
rooms4,
18 and used
a nanostructured UV-reflective wall coating that significantly reduced the time
(from 25 minutes to 5 minutes for MRSA and from 44 minutes to 9 minutes for C. difficile spores) necessary to
decontaminate a room using a UV-C-emitting device.19
