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 74

Fig. 4.3 Concentration of bacteria associated with high touch objects associated with the built
clinical environment and HAI are linked. A significant association (p 0.038) was observed

between the microbial burden and the incidence of HAI acquired during patient stay. Briefly,
the burden data from 333 patients were evaluated in the context of an acquisition of a HAI. It was
found that 89 % of HAI occurred amongst patients cared for in rooms where the burden observed
on six high touch objects exceeded a concentration of 500 CFU. Percentage values listed for the
individual quartiles are reflective of the percentage quartile population acquiring an HAI (Adapted
after the figure of Salgado and colleagues [ 70 ])

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disinfection rely on discontinuous modalities of application in order to reduce the
environmental bacterial burden [ 34 ]. Hydrogen peroxide vapor is introduced as a gas
into a sealed room. Ultraviolet light achieves its effectiveness through the transient
transmission of germicidal radiation within an unoccupied room. Consequently, like
the EPA registered disinfectants regularly used to disinfect patient rooms subsequent
to cleaning, both UV and HPV will likely suffer from the same limitations of the
rapid restoration of the bacterial burden intrinsic to high touch objects.
In addressing the question of whether or not the strategic placement of copper
might ameliorate the rate with which HAI are acquired, Salgado and colleagues
[ 70 ] found from the conduct of a multi-center trial that the limited placement of
copper as described by Schmidt and colleagues [ 75 ] resulted in a significant
reduction to the HAI rate and/or MRSA or VRE colonization rate in medical
intensive care rooms (ICU). The collective rate for HAI infection or MRSA/VRE
colonization was found to be significantly lower by 42 % (7.1 %) in the copper arm
of the study when compared against the (12.3 %) rate observed in the control rooms
(p 0.02). When the data were considered separately for HAI alone, the rate of

infection was significantly reduced (58 %) from 8.1 to 3.4 % (p

¼

0.013).
More importantly, these investigators were able to demonstrate that burden and
infection were directly linked. In the analysis of the quartile distribution of HAIs
stratified by microbial burden measured in the ICU rooms during the patient's stay
they learned that there was a significant association between burden and HAI risk
(p

¼

0.038), with 89 % of HAI occurring among patients cared for in a room with a
burden of more than 500 CFU (Fig. 4.3 )[ 70 ].

¼