Biomedical Engineering Reference
In-Depth Information
were found to continuously kill greater than 99.9 % of Gram-negative and Gram-
positive bacteria within 2 h of exposure even after repeated contamination illustrating
how solid copper surfaces will inhibit the buildup of microorganisms between routine
cleaning and sanitizing steps.
The public health claims attributed to solid copper have been evaluated to limit
the bacterial burden found on commonly touched surfaces and objects in active
healthcare environments. In a recent hospital trial bacterial reductions up to one
third were recorded using copper alloys in place of plastic or aluminum surfaces on
light switches, door knobs and push plates [ 48 ]. Casey and others [ 20 ] observed a
median microbial reduction of between 90 and 100 % (log 10 1.95-2.0) on copper
surfaced push plates, faucet handles, and toilet seats while Schmidt and colleagues
demonstrated significantly lower bacterial burdens on six HTOs, averaging an
83 % (log 10 1.93) reduction for all of the objects over the course of a 43 month
multi-center trial [ 75 ].
Current cleaning methods can effectively remove pathogens from surfaces but
studies have shown that more than half of the trial surfaces were not adequately
terminally cleaned, and became re-contaminated within minutes [ 4 , 17 ]. The rails of
hospital beds, as a consequence of coincident interactions with patients, HCWs, and
visitors are one of the most frequently touched items found in the built patient care
environment. Schmidt and colleagues found when they quantitatively assessed the
bacterial burden present on bed rails that, through the surfacing of the rail withmetallic
copper, the concentration of bacteria resident on this frequently touched surface was
continuously at or below the threshold representing a risk of transfer regardless of
whether or not the surface was measured before or after routine cleaning [ 77 ].
Further, the environmental monitoring of bed frames has consistently shown that
the rails of hospital beds typically exceed a suggested threshold of risk more than
any other object in the patient's room [ 4 , 50 , 75 , 77 , 103 ]. It was evident that bed
rails covered with solid copper are able to augment cleaning and thereby continu-
ously support the control of the concentration of associated aerobic bacteria. This
observation was consistently maintained in spite of the kinetic nature of care
present in the environment of the ICU. Lower risk concentrations, less than
2.5 CFU/cm 2 , were associated with over 83 % of the sampled beds [ 77 ]. Further,
MRSA and VRE were absent from all but 7 of the 3,938 copper objects sampled
arguing that the risk mitigation provided by copper surfaces might be greater than
the average concentrations reported suggest [ 77 ].
Weber and Rutala [ 99 ] in their commentary of the evaluation of no-touch copper
conducted by Karpanen and colleagues argued that it was impractical or impossible
to coat each of the environmental surfaces with copper [ 39 ]. However, the data
provided by Schmidt and colleagues suggest that the strategic placement of solid
copper surfaces in high touch areas is key, and offers a novel strategy to limit the
bacterial burden on a continuous basis [ 75 ]. Copper-alloyed surfaces offer a contin-
uous way to limit and/or control the environmental burden. Hospital and environ-
mental services need not perform additional steps, follow complex treatment
algorithms, obtain “buy-in” from other providers or require additional training or
oversight. The other 'no touch' methods presently in wide scale use for room
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