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Potential of copper alloys to kill bacteria and reduce hospital infection rates

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Internal Medicine Review Copper alloys kill bacteria and reduces infections Month. 2017
Copyright 2016 Internal Medicine Review. All Rights Reserved. Vol. 3, Issue 3
1
Potential of copper alloys to kill bacteria and reduce hospital infection rates
Harold T. Michels1, Corinne A. Michels2
Author Details:
1 Copper Development
Association, 260
Madison Avenue, New
York, NY 10016
2 Biology Department,
Queens College, City
University of New York,
65-30 Kissena
Boulevard, Queens, NY
11367
Correspondence:
Harold T, Michels, PhD,
Copper Development
Assoc., 260 Madison
Ave., New York, NY
10016; 212-251-7224
E-mail:
harold.michels@
copperalliance.us
Abstract
A large body of peer-reviewed literature has demon-
strated in laboratory testing that placing bacteria in a
highly concentrated bacterial inoculum onto copper alloy
surfaces results in their rapid death. A smaller but
convincing number of studies indicate that bacteria die on
the surfaces of hospital room components made from
copper alloys. Will the ability of copper alloys to kill
bacteria translate into an ability to reduce the rate of
hospital-acquired infections (HAIs)? This review
addresses this question. In particular, the results of a
clinical trial in which HAI rates are significantly reduced
after introducing copper alloys components into Intensive
Care Units of three hospitals will be presented. The
findings suggest that copper alloys enhance hospital
hygiene protocols because they act passively 24/7/365
requiring neither training nor human intervention to kill
bacteria and reduce hospital-acquired infections.
Keywords: Antimicrobial copper alloys, hospital-
infections (HAIs), clinical trial, bacterial burden,
infection rates, VRE, MRSA, contact killing
Internal Medicine Review Copper alloys kill bacteria and reduces infections Month. 2017
Copyright 2016 Internal Medicine Review. All Rights Reserved. Vol. 3, Issue 3
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Introduction
Hospital-acquired infections (HAIs),
or those infections the patient develops
while in the hospital, continue to be a
concern because they are not only costly to
treat, but more importantly, cause human
suffering and even death. It was reported
that, in 2002, 1.7 million patients develop an
infection while being cared for in U.S.
hospitals and about 99,000 die each year (1).
Annual treatment cost alone for these
infections is estimated to be in the range of
$35 billion (2). This translates into
approximately 4,600 infections resulting in
about 274 deaths each day. In spite of
extensive efforts to increase hand-washing
compliance an obvious, very simple, and
important method to help reduce
transmission of bacteria has not been
sufficient on its own to solve the infection
problem.
Surface disinfectants are another
widely employed and useful method to help
reduce the amount of bacterial on
environmental surfaces. Evidence that
contaminated surfaces can function as
transmission vectors for hospital pathogens
is clear and control of surface contaminants
should be an effective approach to
controlling HAIs (3). Hygiene standards for
surface cleanliness, based upon food
processing industry standards, have been
proposed (4). However, even when
improved hand washing compliance and
diligent surface hygiene disinfection are
combined, hospital infections are still a
serious health issue. Newer technologies,
such as UV light units (5, 6) and various
hydrogen peroxide (HP) systems (6), can
effectively decontaminate hospital rooms,
but, when added the hand washing and
surface disinfection, HAIs are still not
completely controlled. All the above
approaches hand washing, surface
disinfection, UV light and HP systems
have one thing in common, they are episodic
or one-time approaches. Therefore, as soon
as the decontamination process ends,
microbial contaminants can again begin to
accumulate. Adding an additional
technology that is continuously active
antimicrobial copper alloys can alleviate
this problem. Placing surfaces made from
100% antimicrobial copper alloys will
provide a continuously active solid surface
that kills bacteria on contact and thus has the
potential to reduce infections. Here we
review the clinical evidence supporting this
potential.
Laboratory Research
A multitude of laboratory studies
have shown that a wide variety of bacteria,
both Gram-positive and Gram-negative, are
killed after being placed on copper alloys
surfaces, including “hospital superbugs”
such as Methicillin-Resistant
Staphylococcus aureus (MRSA) and
Vancomycin-Resistant Enterococcus (VRE).
Many of these studies have been
summarized in previously published reviews
(7, 8). Also described elsewhere is the
metallurgy of various antimicrobial copper
alloys and their postulated killing
mechanisms (8). These studies indicate that
copper alloy surfaces act as an effective
biocide not only on a broad range of bacteria
but also are active against fungi and
permanently inactivate viruses. Table 1 lists
the microorganisms that have shown
sensitivity to copper alloy surface contact
killing.
Clearly, copper alloy surfaces have
the potential to be useful in controlling a
wide variety of microbes in the hospital
setting but this needs to be confirmed in
clinical trials. Laboratory tests are
conducted under ideal controlled conditions.
The surfaces of the test samples are
sanitized prior to being inoculated with a
known concentration of a known strain of
bacteria. In contrast, clinical samples are
Internal Medicine Review Copper alloys kill bacteria and reduces infections Month. 2017
Copyright 2016 Internal Medicine Review. All Rights Reserved. Vol. 3, Issue 3
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collected in hospitals by taking swabs from
the surfaces of components. One does not
know when the surface became
contaminated and the hospital surface is
typical contaminated with several different
species of bacteria. The surfaces analyzed
in a clinical test may also contain residues
from prior cleaning solutions, oil from the
hands after being touched, and other
chemical contaminants. Also noteworthy is
that, in laboratory test conditions, the
bacterial inoculum concentration is typically
very high, on the order of 10 million colony-
forming units per sq. cm. (107 CFU/cm2).
When the surface of a hospital component is
sampled, swabs are usually taken from 100
cm2 area and bacterial contamination ranges
from 1,000 to 10,000 CFU/ 100 cm2,
depending on when the surface was cleaned
or the frequency at which the surface is
touched.
As explained above, laboratory tests
are conducted by inoculating samples with
an exceedingly high numbers of bacteria,
well above the amount that would ordinarily
be found on surfaces in hospitals. The
demonstrated ability of copper alloys to kill
these high numbers of bacteria in laboratory
tests is a strong testament to their efficacy
and bodes well for hospital-based studies.
Nonetheless, antimicrobial copper alloys
need to undergo testing in the real life
clinical environment.
Clinical Results microbial reduction
Microbial burden is not only a
surrogate measure of cleanliness. It is also
is an indicator of the propensity to acquire
an infection, as will be discussed in a later
section. A clinical study conducted in a
medical intensive care unit (MICU) in the
United States (9) measured the amount of
bacteria present on 36 standard plastic
patient bed rails immediately before
cleaning and at set time intervals of 0.5, 2.5,
4.5, and 6.5 hours after cleaning with either
of two hospital-approved disinfectants. The
bacterial burden rebounded 30% at 6.5 hours
after using one type of disinfectant and 45%
at 2.5 hours after using another disinfectant.
Thus, cleaning helps reduce bacterial
burden, but its benefit is dissipated in a
matter of hours.
In a subsequent study in the same
hospital setting (10), three beds were custom
fitted with copper alloy surface caps to
cover the bed rails, with three standard
plastic beds serving as control surfaces. The
sampling schedule was the same as
described in the previous study (9), but in
contrast to the previous study, only one
hospital-approved disinfectant was used.
The bacterial burdens found on the copper
rails were significantly lower than those
measured on the standard plastic bed rails,
as shown in Figure 1. Note that the copper
rail bacterial burden approaches the
suggested terminal cleaning target of 250
CFU/100 cm2, which is the cleaning goal
after a room is vacated but prior to
introducing the next patient.
In the United States (11), another
small trial was conducted in an outpatient
infectious disease clinic. In this
environment, surfaces are touched by many
patients and rapidly become contaminated.
Copper alloys were installed on two
phlebotomy chairs. The tops of the wooden
arms of the chairs were inlaid with a wide
copper alloy strip, but the wood remained on
the sides of the arms. In addition, the plastic
trays attached to the chair arms were
replaced with copper alloy trays. Over 15
weeks, 437 patients used the chairs. Results
were compared to the control surfaces, the
wooden arms and plastic trays on the chairs
in adjacent rooms. Cleaning frequency and
methods were the same. The copper tray
chairs showed an 88% reduction in bacterial
burden and the copper alloy inlaid arm
showed a 90% reduction compared to the
standard surfaces or controls. Even the
Internal Medicine Review Copper alloys kill bacteria and reduces infections Month. 2017
Copyright 2016 Internal Medicine Review. All Rights Reserved. Vol. 3, Issue 3
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remaining wood at the side of the copper
alloy inlaid chair arm displayed a 70%
reduction, which was attributed to lower rate
of cross contamination from the copper alloy
surface. Fewer bacteria survived on the
copper alloy surface and therefore a smaller
number of bacteria were available to be
transferred to the adjacent wood on the side
of the arm of the chair.
A study (12) involving stethoscopes
was conducted in the United States at two
sites, a pediatric emergency division and
various adult medical/surgical settings
including intensive care units. Copper alloy
equivalents of commercial cardiology
stethoscopes were fabricated. Specifically,
the diaphragm, ear tubes braiding over the
polyvinyl chloride tubing, and chest piece,
were replaced with copper alloys. The same
parts of the commercial stethoscopes served
as controls. The study, which utilized 32
stethoscopes, involved 21 healthcare
providers, specifically 14 in the pediatric
setting and 7 in the adult setting. They were
not informed of the antimicrobial properties
of copper alloys and were blinded with
regard to the purpose of the trial. The study
team provided either control or copper
stethoscopes to the healthcare workers on an
alternate basis. The devices were collected
after one week of use on four occasions over
90 days, and colony counts were measured.
In the adult setting, where only the copper
and epoxy standard control diaphragms were
evaluate, the microbial burden on the copper
stethoscopes was 5 CFU/cm2 versus 10
CFU/cm2 on the controls, and the results
were significant (p=0.0051). In the pediatric
setting, the burden on the copper
stethoscopes was 4 CFU/cm2 versus 16
CFU/cm2 on the controls, but the results
failed to reach significance (p=0.089),
presumably because the sample size was too
small. Multiple surfaces were also sampled
in the pediatric setting: the diaphragm, the
ear tubes, and the braiding over the
polyvinyl chloride tubing. The braiding
over the chest piece was not sampled
because of its irregular shape and surface
area. In the pediatric setting, the aerobic
colony counts recovered from the copper
alloy surfaces were 11.7 CFU/cm2, an order
of magnitude lower than that found on the
control surfaces, at 127.1 CFU/cm2, and
achieved strong statistical significance
(p<0.00001).
In a clinical trial conducted in a
hospital medical ward in England (13), three
copper alloy components were installed:
sink faucet handles, door push plates at the
ward entrance, and toilet seats. Each of
these surfaces was sampled once each week
at 7 am and 5 pm over a ten-week period, as
were equivalent non-copper control items in
the ward. After five weeks the components
were interchanged. The median bacterial
burden reduction on the copper components
compared to the control components ranged
from 90% to 100%.
In a second larger clinical trial
conducted in the medical ward of the same
hospital in England mentioned above (14),
several frequently touched components
made from copper alloys were installed
including door handles and push plates, grab
rails, light switches and pull cord toggle
switches, over-the-patient bed tables,
dressing trolleys, as well as portable
commodes, sink taps and fittings, sinks,
toilet seats and flush handles. The above
copper components and the controls were
sampled once a week for 24 weeks, with the
locations of the components being switched
after 12 weeks. The microbial burden on 8
of the 14 copper alloy components was
significantly lower than those found on the
standard control components. While the
other 6 copper alloy components also
exhibited a reduction in bacterial burden, it
was found not to be statistically significant.
However, indicator organisms recovered
from all surfaces provide some additional
Internal Medicine Review Copper alloys kill bacteria and reduces infections Month. 2017
Copyright 2016 Internal Medicine Review. All Rights Reserved. Vol. 3, Issue 3
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insights. The surfaces of copper alloy
components harbored significantly fewer
VRE, MRSA and coliform bacteria,
compared to the control surfaces.
A clinical trial was conducted in a
hospital in Germany (15), in patient rooms,
rest rooms, and staff rooms, and in
oncology, respiratory treatment, and
geriatric wards of a hospital. A total of 48
aluminum door push plates were replaced
with copper alloy plates. An equal number
aluminum doorknobs and plastic light
switches were also replaced with
components made from copper alloys.
During 16 weeks in the summer and 16
weeks in the winter, samples were taken
from the copper alloy surfaces and control
surfaces. The total bacterial burden on the
copper alloy components was 63% of that
found on the control components. The total
bacterial burden on copper alloy doorknobs
was much lower than that found aluminum
doorknobs. The bacterial burden on the both
the copper alloy push plates and light
switches was only slightly lower than that
found on the controls made of aluminum or
plastic. In addition the bacterial burden seen
on the aluminum doorknobs, while higher
than that found on the copper doorknobs,
was also much higher than seen on the other
control components. It was suggested that
this difference may be simply because that
doorknobs are more frequently touched
relative to the other components. While the
results of this trial did not achieve the same
high levels of microbial burden reduction
observed in other trials, the impact of the
presence of antimicrobial copper alloys is
apparent.
A clinical trial conducted in a
Pediatric ICU in Chile involved 8 room with
copper components and 8 control rooms
with standard components (16). The copper
surfaces included in the study were bed rails,
bed rail levers, IV poles, faucet handles, and
a workstation surface. The results indicated
that copper alloys efficacy was equivalent to
that observed in an adult ICU (17). The
copper bed rail, the most frequently touched
object in the rooms, showed the greatest
bacterial burden. Interestingly, it was
reported that the introduction of copper
alloys in the study rooms suppressed the
microbial burden recovered from
components in the nearby control rooms,
collected prior to the introduction of the
copper components. It is suggested that this
may be a result of suppressed cross
contamination.
Another clinical trial in the United
States was conducted in the medical-surgical
suite in a small rural hospital (18). Six of
the 13 single rooms were converted to
copper, as were three of the five double
rooms. The installed copper alloy
components included door levers, alcohol
gel dispenser push plates, light switches,
bedside table pulls, over-bed tables, toilet
flush valve lever, grab bars, faucet handles,
and soap dispenser push plates. Copper
alloy beds were not fabricated, but a
commercial copper alloy stretcher bed, used
for patient transport by the emergency
department, was included in the trial. The
mean bacterial burden recovered from the
copper alloy components was 140 CFU/100
cm2, which is well below the 8,414
CFU/100 cm2 found on the controls and
slightly below the terminal cleaning target
level of 250 CFU/100 cm2.
A large clinical trial was conducted
in the Unites States in the ICUs of three
hospitals over 43-month period (17). At
month 23, six copper components were
installed in eight of the sixteen ICU rooms.
The components were the rail of the patient
bed, the nurses call button, the arms of the
visitor’s chair, the over-the-patient bed
table, the intravenous (IV) drip pole, and a
data input device that varied by hospital.
The latter was either a computer mouse, the
bezel on a touch screen, or a strip where the
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Copyright 2016 Internal Medicine Review. All Rights Reserved. Vol. 3, Issue 3
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palm of the hand rests on a laptop computer.
Microbial burden was measured on the six
copper components and six standards
components that served as controls over the
next 21 months. The data collected from the
six objects is presented in Figure 2. Note
that the control bed rail has the highest level
of microbial burden, but this is dramatically
lower on the copper bed rail. The bed rail is
the major point of interaction between
patients, healthcare workers and visitors,
which may explain the high microbial
burden on the plastic bed rail. The controls
for the nurses call button and arms of the
visitor’s chair also had high levels of
contamination. However, the bacterial
burden on all the copper components were
below that seen on the standard or control
surfaces, except for the data input devices,
which is an anomaly. The contamination
levels of both the control and copper data
input devices were both low. The use of
these devised is restricted to healthcare
professionals who are more aware of the
potential for infections and may clean them
and their hands more frequently.
Clinical Results infection reduction
A follow-on study (19), conducted at
the same facility in Chile as described
previously (16), analyzed hospital-acquired
infections in 261 patients in the copper
rooms and 254 in the control rooms. The
study found that infection rates were 10.6
per 1000 patient days in the copper room
and 13.0 in the control rooms. This
translated into a relative risk reduction of
0.19. These authors reported that the above
result was not did not achieve statistically
significance and concluded, “Conducting
clinical trials to assess interventions that
may impact HAI rates is very challenging.”
A next phase of the previously
mentioned clinical trial in the Unites States
(17), also conducted in the ICUs of three
hospitals, shifted its focused from microbial
burden to infection rates (20). The sampling
continued as previously described but the
healthcare workers were not informed that
that approval had be granted by the Internal
Review Boards of all the involved
institutions to track infections. The number
of infections over the same time period in
copper and control rooms were compared.
Clinicians at each hospital determined
incidents of hospital-acquired infections,
according to National Safety Network
definitions. However, the clinicians were
masked or blinded with regard to the
identity of patients. The infection rates were
3.4% in the copper rooms (10 infections in
294 patients) and 8.1% in the control rooms,
or 26 fewer infections than in the 320
control patients. A high level of statistical
significance (p value =0.013) was attained.
This equates to 58% reduction in infections
as a result of introducing only six copper
items into each copper room, comprising
less than 10% of their surface area. The data
plotted in Figure 3, collected during this
clinical trial, indicates that the propensity to
acquire an infection increases as the
microbial burden increases. Thus, infection
rates correlate with surface contamination
levels. The figure includes all data from both
copper and control rooms, and is statistically
significant, as indicated by its p value of
0.038. These results (20) can be used to
calculate the cost of recovery time for
outfitting a copper alloy room. The
additional cost to fabricate the copper
components was about $52,000. The cost to
treat an infection ranges from $28,400 to
$33,800 (2). The number of infections
prevented in this trial is 14. Based upon the
above cost per infection, the time to recover
the cost of outfitting the ICU with copper
components is calculated as 37 to 44 days
(7).
Internal Medicine Review Copper alloys kill bacteria and reduces infections Month. 2017
Copyright 2016 Internal Medicine Review. All Rights Reserved. Vol. 3, Issue 3
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Conclusions
There is a considerable body of
literature that indicates that bacteria die
when they come into contact with copper
alloy surfaces in the laboratory as well as a
meaningful but smaller number of
publications that illustrate that copper alloys
kill bacteria in the clinical setting. While
additional clinical trials are needed to
confirm that the deployment of solid copper
alloy surfaces can reduce infection rates,
there is ample evidence currently available
to encourage hospitals and other patient
treatment centers to adopt the use of
antimicrobial copper alloys as part of their
infection control protocols.
The copper alloy components used in
the studies referenced here were fabricated
from 100% solid metal. The copper alloys
used must contain at least 60% copper to be
considered for EPA registration, which is
required in make public health claims in the
United States related to their ability to kill
specific bacteria. The copper alloy was not
applied as a coating, which can wear off, or
introduced as particles in proprietary plastic
matrix that make up less than 5% of the
surface area.
The initial cost of outfitting a copper
alloy room may be perceived as an issue.
However, the extra cost can be quickly
recovered because infections are expensive
to treat. Based upon the number of
infections prevented in ICUs of three
hospitals (20), the extra cost of copper
components was recaptured in less than two
months (7). It should also be noted that
some hospitals would loose a portion of
their Medicare funding under the Hospital
Acquired Condition Reduction Program (21)
if hospital-acquired infections occur in their
facilities. It is important to note that there is
no identified medical risk in using
antimicrobial copper alloy hospital room
components. Humans have commonly used
copper alloys since the Bronze Age, over 5
millennia ago, without any evidence of
harm. Clearly, placing copper alloy
components in the human environment has
the potential to reduce infections, may avoid
the above-mentioned financial penalty, and
will lower infection treatment costs.
Antimicrobial copper alloys may also have
intangible benefits, such as, demonstrating
to your patients that your organization cares
about their wellbeing.
Perhaps the greatest potential benefit
of wider use of antimicrobial copper alloys
to control infection has the potential to
inhibit the emergence of new antibiotic
resistant strains. Based on reports from the
U.S. Center for Disease Control, the abuse
and overuse of antibiotics is a major cause
of the emergence of resistant bacteria
(http://www.cdc.gov/drugresistance/). The
use of subclinical levels of antibiotics in
raising animals for human consumption is a
serious contributor to this problem (22).
Also to be considered is that horizontal gene
transfer of antibiotic resistance, a major
cause of the spread of multidrug resistance
in bacteria, is essentially blocked by copper
alloy surface killing because the bacteria die
rapidly with few to no survivors (23).
Nearly 200 facilities have installed
antimicrobial copper products provided by
U.S. based EPA registered manufacturers, in
37 states and 13 countries. These
installations include healthcare facilities,
schools and universities, office buildings,
fitness facilities, laboratories and
restaurants. Copper alloys are a passive
antimicrobial technology that works 24
hours/day, 7 days/week, and 365 days/year.
Its effectiveness in killing bacteria and
potentially reducing infections requires
neither specially trained personnel nor
human intervention. A wide array of
commercial products made from EPA-
registered antimicrobial copper alloys is
available for integration into the healthcare
environment.
Internal Medicine Review Copper alloys kill bacteria and reduces infections Month. 2017
Copyright 2016 Internal Medicine Review. All Rights Reserved. Vol. 3, Issue 3
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In summary, consideration should be
given to deploy components made from
solid metal antimicrobial copper alloys as an
additional tool in the fight to reduce
hospital-acquired infections.
Acknowledgements
We thank Adam Estelle of the Copper
Development Association for his useful
input, as well as the many investigators with
whom we have interacted over the years,
especially Professors Michael G. Schmidt
and C. William Keevil.
Conflict of Interest
The authors have no conflict of interest
directly relevant to this manuscript.
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Internal Medicine Review Copper alloys kill bacteria and reduces infections month. 2017
Table 1. Microorganisms that are known to die on copper alloy surfaces (taken from (8))
Microorganism
Reference
Bacterial species
Acinetobacter species (MDR, other strains)
(24), (25), (26), (27)
Bacillus anthrax, B. cereus, B. subtilis (vegetative cells, not spores)
(28), (29), (30)
Brachybacterium conglomernatum
(27)
Brucella melitensis
(29)
Burkholderia species
(29), (31), (32)
Campylobacter jejuni
(33)
Clostridium difficile (vegetative cells, not spores)
(34), (35)
Deinococcus radiodurans
(28)
Enterobacter species
(25), (36), (37)
Enterococci species (vancomycin resistant, other strains)
(38), (39), (40), (41), (42)
Escherichia coli (various strains)
(28), (38), (43), (44), (45)
Francisella tularensis
(29)
Klebsiella pneumonia
(23), (24), (25)
Legionella pneumophila
(46), (47), (48), (49)
Listeria monocytogenes
(50), (51)
Mycobacterium tuberculosis
(24)
Pantoea stewartii
(27)
Pseudomonas species
(25), (26), (27), (36), (38), (41)
Salmonella enterica
(33), (39), (52)
Staphylococcus aureus (MRSA, other strains); other Stapyloccoccus
species
(26), (27), (38), (53), (54), (55)
Yersinia pestis
(29)
Viruses
Coronavirus 229E (human)
(56)
Influenza A
(57)
Norovirus (murine, human)
(40), (58), (59)
T2 bacteriophage
(60)
Vaccinia, Monkeypox
(29)
Fungi
Aspergillus species
(46)
Candida albicans
(24), (46), (61)
Fusarium species
(46)
Penicillium chrysogenum
(46)
Saccharomyces cerevisiae
(61)
Internal Medicine Review Copper alloys kill bacteria and reduces infections Month. 2017
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14
Figure 1: Microbial burden found on the standard plastic rail (filled circles) and copper rail
(open circles). The dashed line is the desired target microbial burden after terminal
cleaning of 250 CFU/100 cm2 (taken from (10)).
Internal Medicine Review Copper alloys kill bacteria and reduces infections Month. 2017
Copyright 2016 Internal Medicine Review. All Rights Reserved. Vol. 3, Issue 3
15
Figure 2: Microbial burden found on six objects in standard control rooms (dark gray bars) and
copper rooms (light gray bars) in hospital intensive care units (ICUs) (taken from (17)).
Internal Medicine Review Copper alloys kill bacteria and reduces infections Month. 2017
Copyright 2016 Internal Medicine Review. All Rights Reserved. Vol. 3, Issue 3
16
Figure 3. Relationship between microbial burden measured in ICU rooms and the occurrences of
hospital-acquired infects (HAIs) (taken from (20)).
... There are now numerous published laboratory results plus a smaller number of clinical trials indicating that copper alloys can be an effective ally in the battle against pathogen-borne disease, not just today but for years to come [8][9][10] . And with the rapid growth in the number of facilities testing antimicrobial copper-including hospitals, clinics, physical fitness and sports facilities, office buildings, schools, res-taurants, and even mass transit systems-the evidence is likely to mount. ...
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Background: Stethoscopes may serve as vehicles for transmission of bacteria among patients. The aim of this study was to assess the efficacy of antimicrobial copper surfaces to reduce the bacterial concentration associated with stethoscope surfaces. Methods: A structured prospective trial involving 21 health care providers was conducted at a pediatric emergency division (ED) (n = 14) and an adult medical intensive care unit located in tertiary care facilities (n = 7). Four surfaces common to a stethoscope and a facsimile instrument fabricated from U.S. Environmental Protection Agency-registered antimicrobial copper alloys (AMCus) were assessed for total aerobic colony counts (ACCs), methicillin-resistant Staphylococcus aureus, gram-negative bacteria, and vancomycin-resistant enterococci for 90 days. Results: The mean ACCs collectively recovered from all stethoscope surfaces fabricated from the AMCus were found to carry significantly lower concentrations of bacteria (pediatric ED, 11.7 vs 127.1 colony forming units [CFU]/cm(2), P < .00001) than their control equivalents. This observation was independent of health care provider or infection control practices. Absence of recovery of bacteria from the AMCu surfaces (66.3%) was significantly higher (P < .00001) than the control surfaces (22.4%). The urethane rim common to the stethoscopes was the most heavily burdened surface; mean concentrations exceeded the health care-associated infection acquisition concentration (5 CFU/cm(2)) by at least 25×, supporting that the stethoscope warrants consideration in plans mitigating microbial cross-transmission during patient care. Conclusions: Stethoscope surfaces fabricated with AMCus were consistently found to harbor fewer bacteria.
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Objective: To assess the ability of copper alloy surfaces to mitigate the bacterial burden associated with commonly touched surfaces in conjunction with daily and terminal cleaning in rural hospital settings. Design: A prospective intention-to-treat trial design was used to evaluate the effectiveness of cooper alloy surfaces and respective controls to augment infection control practices under pragmatic conditions. Setting: Half of the patient rooms in the medical-surgical suite in a 49-bed rural hospital were outfitted with copper alloy materials. The control rooms maintained traditional plastic, metal, and porcelain surfaces. Methods: The primary outcome was a comparison of the bacterial burden harbored by 20 surfaces and components associated with control and intervention areas for 12 months. Locations were swabbed regardless of the occupancy status of the patient room. Significance was assessed using nonparametric methods employing the Mann-Whitney U test with significance assessed at P < .05. Results: Components fabricated using copper alloys were found to have significantly lower concentrations of bacteria, at or below levels prescribed, upon completion of terminal cleaning. Vacant rooms were found to harbor significant concentrations of bacteria, whereas those fabricated from copper alloys were found to be at or below those concentrations prescribed subsequent to terminal cleaning. Conclusions: Copper alloys can significantly decrease the burden harbored on high-touch surfaces, and thus warrant inclusion in an integrated infection control strategy for rural hospitals.
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Exposure to dry copper alloy surfaces, such as brass, kills a wide spectrum of microorganisms including Gram negative and Gram positive bacteria and fungi, and permanently inactivates several types of viruses. In laboratory testing, greater than 99.9% killing occurred within a 2-hour period when the microorganism was exposed to the copper alloy samples at room temperature and typical indoor humidity levels. Included in the studies were disease-causing bacteria such as E. coli O157: H7 and hospital “super-bugs” such as Methicillin-Resistant Staphylococcus aureus (MRSA), and Vancomycin-Resistant Enterococci (VRE). The results of these laboratory tests will be reviewed here. The mechanism(s) of action of copper alloy surface killing is still under investigation and progress on this important area of research will be described. It is important to note that mutations that provide resistance to copper alloy surface exposure have not been reported. These results suggest that copper alloy surfaces could be a powerful tool against the transmission of infectious disease in public settings, most particularly hospitals. In a clinical trial, the amount of live bacteria found on components made of copper alloys was compared to that found on components made from standard materials and shown to be 83% lower. Most significantly, when infection rates were tracked in these hospital rooms with the copper components and compared to rooms containing the standard components, it was found that the infection rates were reduced by a statistically significant 58%. Thus, the widespread deployment of copper alloy components to frequently touched surfaces, such as door knobs and hand rails, has the potential to significantly reduce the rate of transmission of infections in the clinical settings and public-use spaces such as schools and transit systems.
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Background: Studies have consistently shown that copper alloyed surfaces decrease the burden of microorganisms in health care environments. This study assessed whether copper alloy surfaces decreased hospital-associated infections in pediatric intensive and intermediate care units. Methods: Admitted infants were assigned sequentially to a room furnished with or without a limited number of copper alloyed surfaces. Clinical and exposure to intervention data were collected on a daily basis. To avoid counting infections present prior to admission, patients who stayed in the hospital <72 hours were excluded from analysis. Health care-associated infections (HAIs) were confirmed according to protocol definitions. Results: Clinical outcomes from 515 patients were considered in our analysis: 261 patients from the intervention arm of the study, and 254 from the control arm. Crude analysis showed an HAI rate of 10.6 versus 13.0 per 1,000 patient days for copper- and non-copper-exposed patients, respectively, for a crude relative risk reduction (RRR) of 0.19 (90% confidence interval, 0.46 to -0.22). Conducting clinical trials to assess interventions that may impact HAI rates is very challenging. The results here contribute to our understanding and ability to estimate the effect size that copper alloy surfaces have on HAI acquisition. Conclusions: Exposure of pediatric patients to copper-surfaced objects in the closed environment of the intensive care unit resulted in decreased HAI rates when compared with noncopper exposure; however, the RRR was not statistically significant. The clinical effect size warrants further consideration of this intervention as a component of a systems-based approach to control HAIs.
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Background: Health care-associated infections result in significant patient morbidity and mortality. Although cleaning can remove pathogens present on hospital surfaces, those surfaces may be inadequately cleaned or recontaminated within minutes. Because of copper's inherent and continuous antimicrobial properties, copper surfaces offer a solution to complement cleaning. The objective of this study was to quantitatively assess the bacterial microbial burden coincident with an assessment of the ability of antimicrobial copper to limit the microbial burden associated with 3 surfaces in a pediatric intensive care unit. Methods: A pragmatic trial was conducted enrolling 1,012 patients from 2 high acuity care units within a 249-bed tertiary care pediatric hospital over 12 months. The microbial burden was determined from 3 frequently encountered surfaces, regardless of room occupancy, twice monthly, from 16 rooms, 8 outfitted normally and 8 outfitted with antimicrobial copper. Results: Copper surfaces were found to be equivalently antimicrobial in pediatric settings to activities reported for adult medical intensive care units. The log10 reduction to the microbial burden from antimicrobial copper surfaced bed rails was 1.996 (99%). Surprisingly, introduction of copper objects to 8 study rooms was found to suppress the microbial burden recovered from objects assessed in control rooms by log10 of 1.863 (73%). Conclusion: Copper surfaces warrant serious consideration when contemplating the introduction of no-touch disinfection technologies for reducing burden to limit acquisition of HAIs.
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This study explores the role of membrane phospholipid peroxidation in the copper alloy mediated contact killing of Bacillus subtilis, a spore-forming gram-positive bacterial species. We found that B. subtilis endospores exhibited significant resistance to copper alloy surface killing but vegetative cells were highly sensitive to copper surface exposure. Cell death and lipid peroxidation occurred in B. subtilis upon copper alloy surface exposure. In a sporulation-defective strain carrying a deletion of almost the entire SpoIIA operon, lipid peroxidation directly correlated with cell death. Moreover, killing and lipid peroxidation initiated immediately and at a constant rate upon exposure to the copper surface without the delay observed previously in E. coli. These findings support the hypothesis that membrane lipid peroxidation is the initiating event causing copper surface induced cell death of B. subtilis vegetative cells. The findings suggest that the observed differences in the kinetics of copper-induced killing compared to E. coli result from differences in cell envelop structure. As demonstrated in E. coli, DNA degradation was shown to be a secondary effect of copper exposure in a B. subtilis sporulation-defective strain. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.
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This is a translational science article that discusses copper alloys as antimicrobial environmental surfaces. Bacteria die when they come in contact with copper alloys in laboratory tests. Components made of copper alloys were also found to be efficacious in a clinical trial. There are indications that bacteria found on frequently touched environmental surfaces play a role in infection transmission. In laboratory testing, copper alloy samples were inoculated with bacteria. In clinical trials, the amount of live bacteria on the surfaces of hospital components made of copper alloys, as well as those made from standard materials, was measured. Finally, infection rates were tracked in the hospital rooms with the copper components and compared to those found in the rooms containing the standard components. Greater than a 99.9% reduction in live bacteria was realized in laboratory tests. In the clinical trials, an 83% reduction in bacteria was seen on the copper alloy components, when compared to the surfaces made from standard materials in the control rooms. Finally, the infection rates were found to be reduced by 58% in patient rooms with components made of copper, when compared to patients' rooms with components made of standard materials. Bacteria die on copper alloy surfaces in both the laboratory and the hospital rooms. Infection rates were lowered in those hospital rooms containing copper components. Thus, based on the presented information, the placement of copper alloy components, in the built environment, may have the potential to reduce not only hospital-acquired infections but also patient treatment costs. © The Author(s) 2015.
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The emergence and spread of antibiotic resistance demanded novel approaches for the prevention of nosocomial infections, and metallic copper surfaces have been suggested as an alternative for the control of multidrug-resistant (MDR) bacteria in surfaces in the hospital environment. This study aimed to evaluate the antimicrobial activity of copper material for invasive MDR nosocomial pathogens isolated over time, in comparison to stainless steel. Clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) (n:4), OXA-23 and OXA-58 positive, MDR Acinetobacter baumannii (n:6) and Pseudomonas aeruginosa (n:4) were evaluated. The antimicrobial activity of coupons containing 99 % copper and a brass alloy containing 63 % copper was assessed against stainless steel. All the materials demonstrated statistically significant differences within each other for the logarithmic reduction of microorganisms. Among the three materials, the highest reduction of microorganisms was seen in 99 % copper and the least in stainless steel. The result was statistically significant especially for 0, 2, and 4 h (P = 0.05). 99 % copper showed a bactericidal effect at less than 1 h for MRSA and at 2 h for P. aeruginosa. 63 % copper showed a bactericidal effect at 24 h for P. aeruginosa strains only. Stainless steel surfaces exhibited a bacteriostatic effect after 6 h for P. aeruginosa strains only. 99 % copper reduced the number of bacteria used significantly, produced a bactericidal effect and was more effective than 63 % copper. The use of metallic copper material could aid in reducing the concentration of bacteria, especially for invasive nosocomial pathogens on hard surfaces in the hospital environment.
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Human norovirus (HuNoV) represents a significant public health burden worldwide and can be environmentally transmitted. Copper surfaces have been shown to inactivate the cultivable surrogate murine norovirus, but no such data exist for HuNoV. The purpose of this study was to characterize the destruction of GII.4 HuNoV and virus-like particles (VLPs) when exposed to copper alloy surfaces. Fecal suspensions positive for a GII.4 HuNoV outbreak strain or GII.4 virus-like particles (VLPs) were exposed to copper alloys or stainless steel for 0 to 240 min and recovered by elution. HuNoV genome integrity was assessed by RT-qPCR (without RNase treatment), and capsid integrity was assessed by RT-qPCR (with RNase treatment), transmission electron microscopy (TEM), SDS-PAGE/Western blot analysis, and a histo-blood group antigen (HBGA) binding assay. Exposing fecal suspensions to pure copper for 60 min reduced GII.4 HuNoV RNA copy number by approximately 3 log10 when analyzed by RT-qPCR without RNase treatment, and 4 log10 when a prior RNase treatment was used. The rate of reduction in HuNoV RNA copy number was approximately proportional to the percent copper in each alloy. Exposing GII.4 HuNoV VLPs to pure copper surfaces resulted in noticeable aggregation and destruction within 240 min, an 80% reduction in VP1 major capsid protein band intensity in 15 min, and near complete loss of HBGA receptor binding within 8 min. In all experiments, HuNoV remained stable on stainless steel. These results suggest that copper surfaces destroy HuNoV, and may be useful in preventing environmental transmission of the virus in at-risk settings. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
Article
objective. The purpose of this study was to provide a national estimate of the number of healthcare-associated infections (HAI) and deaths in United States hospitals. Methods. No single source of nationally representative data on HAIs is currently available. The authors used a multi-step approach and three data sources. The main source of data was the National Nosocomial Infections Surveillance (NNIS) system, data from 1990-2002, conducted by the Centers for Disease Control and Prevention. Data from the National Hospital Discharge Survey (for 2002) and the American Hospital Association Survey (for 2000) were used to supplement NNIS data. The percentage of patients with an HAI whose death was determined to be caused or associated with the HAI from NNIS data was used to estimate the number of deaths. Results. In 2002, the estimated number of HAIs in U.S. hospitals, adjusted to include federal facilities, was approximately 1.7 million: 33,269 HAIs among newborns in high-risk nurseries, 19,059 among newborns in well-baby nurseries, 417,946 among adults and children in ICUs, and 1,266,851 among adults and children outside of ICUs. The estimated deaths associated with HAIs in U.S. hospitals were 98,987: of these, 35,967 were for pneumonia, 30,665 for bloodstream infections, 13,088 for urinary tract infections, 8,205 for surgical site infections, and 11,062 for infections of other sites. Conclusion. HAIs in hospitals are a significant cause of morbidity and mortality in the United States. The method described for estimating the number of HAIs makes the best use of existing data at the national level.