Copper Helps Control Infection in Healthcare Facilities

Copper Applications in Health & Environment Area

August 2004

By William H. Dresher, Ph.D., P. E.

Clarion Cry | Hospital-acquired Infections | Copper's Role | Most Important Uses | Conclusion | References

CNN News —"Thousands die needlessly from hospital infections” ¹

The news media and the National Centers for Disease Control and Prevention in the United States recently sounded the alarm over infections contracted in hospitals and other healthcare facilities due to lack of proper sanitation procedures. There is widespread concern in the UK also, where nearly 30 percent of patients polled in a 2002 hospital cleanliness survey believe that hygiene standards in UK hospitals are lower than in their own homes.

Copper (as well as brass and other copper alloys), when used as building hardware, plumbing tube and as ions injected directly into potable water, is a significant deterrent to the contraction of disease by the reduction of bacteria and viruses in healthcare facilities. Copper is especially effective in controlling Legionella pneumophila, the bacterium responsible for Legionnaires’ disease.

The Clarion Cry

The death of esteemed ESPN-TV and radio sports reporter and author Dick Schaap in June 2002 due to a hospital-contracted infection during hip replacement surgery brought the issue of hospital-based infections to the public's attention.² In July 2002, the Chicago Tribune further amplified the issue of hospital-based infections in a three-part series, “Tribune Investigation: Unhealthy Hospitals”³. The newspaper's reporters analyzed millions of computerized patient records from the nation’s 5,810 registered hospitals and compiled thousands of state and federal surveys and investigative reports. They found that about 103,000 deaths were linked to hospital infections in 2000 — a figure 14 percent higher than the number reported earlier by the National Centers for Disease Control and Prevention (CDC). The investigation established that nearly three-quarters of the deadly infections (about 75,000) were preventable, the result of unsanitary facilities, germ-laden instruments and unwashed hands. According to the Tribune, deaths linked to hospital infections represent the fourth leading cause of mortality among Americans, behind heart disease, cancer and strokes. These infections kill more people each year than car accidents, fires and drowning combined

Hospital-acquired Infections

According to the CDC, hospital-acquired (or nosocomial) infections affect approximately 2 million persons and result in nearly 88,000 deaths each year in the United States. This is equivalent to one death every 6 minutes. These numbers have grown with each passing year.⁴ The infections annually add an estimated $5 billion to $6.7 billion to U.S. healthcare costs.^{5, 6} CDC has been monitoring such infections since 1970 in their National Nosocomial Infections Surveillance (NNIS) system. According to the CDC, antimicrobial resistant infections in healthcare settings are a major threat to patient safety. Further, bacteria that are resistant to at least one of the antimicrobial agents commonly used to treat those infections cause more than half of hospital infections.

In the UK, approximately 1 in 10 hospitalized patients will acquire an infection after admission. The frequency of nosocomial infections in U.S. hospitals — approximately five to six infections per 100 admissions — has been remarkably steady since the CDC study began in 1975. However, because of a higher patient turnover due to shorter hospital stays, the rate of infections has been going up, from 7.2 per 1000 patient-days in 1975 to 9.8 in 1995 — a 36 percent growth rate! Concluding that more has to be done, the CDC announced, on March 26, 2002, a campaign directed at clinicians to prevent antimicrobial resistance in healthcare settings.⁷

One of the most virulent and prevalent of the nosocomial infections is Methicillin Resistant Staphylococcus Aureus (MRSA). It is one of the new generation of “super bugs” that have developed a resistance to most antibiotics. In the period 1990 to 1996, the three most common gram-positive pathogens — MRSA, coagulase-negative staphylococci and enterococci — accounted for 34 percent of nosocomial infections, and the four most common gram-negative pathogens — E. coli. P. aeruginosa, Enterobacter spp., and Klebsiella pneumoniae — accounted for and additional 32 percent.⁸ L. pneumophila, the bacteria that causes Legionnaires’ disease, while generally associated with infection from public building cooling towers, has also been shown to be a nosocomial infection with fatal consequences.

The CDC has identified six areas of concern and their respective diseases in their comprehensive Draft Guideline for Environmental Infection Control In Healthcare Facilities, 2001.⁹

1. Air – heating, ventilation and air-conditioning systems

a. Aspergillosis and other fungal diseases;
b. Tuberculosis, legionellosis and other bacterial diseases
c. Viral diseases

2. Water – water systems

a. Legionellosis
b. Other Gram-negative bacterial infections
c. Non-tuberculosis mycobacteria
d. Cryptosporidiosis

3. Environmental services

a. Cleaning and disinfection of surfaces

4. Laundry and bedding

5. Animals in healthcare facilities

6. Medical waste

Copper’s Role

So, how can copper help to prevent infections in hospitals? Obviously, copper cannot enforce the washing of hands, but it can help sanitize the water used to wash hands and the surfaces with which hands come in contact. It can also help prevent bacterial and fungal infestation, and — very importantly — it can even help disinfect the air that patients breathe.

The bactericidal, fungicidal and, to some extent, viruscidal properties of copper, copper compounds and alloys of copper have been known for many years.^{10, 11, 12} Indeed, the earliest medical texts refer to the use of copper compounds for wound-healing, i.e., sterilization of wounds,¹³ and there is evidence indicating that copper tubing used for in-hospital water transport and treatment systems may help to reduce the numbers of undesirable bacteria present in water.^{14, 15, 16, 17, 18}

Today, copper, in the form of plumbing tube, copper or copper-alloy surfaces, fungicides and ions injected directly into potable water, has shown it is a significant deterrent to the contraction of fungal and bacterial disease in healthcare (as well as food-processing) facilities. For example, studies at Montana State University found that copper levels as low as 0.007–0.540 mg/l are effective in immobilizing coliform bacteria in drinking water.¹⁹ Viruses require significantly higher levels of copper, on the order of 1,000 mg/l, to be deactivated, although in the presence of an oxidizing agent such as peroxide or chlorine, concentrations of copper as low as 0.05 mg/l are effective.

Studies on swimming pool disinfection at the University of Arizona showed that there is a synergism between copper and chlorine. Concentrations of copper as low as 0.40 mg/l in the presence of concentrations of chlorine as low as 0.02 mg/l were found to be effective in deactivating both bacteriophage MS-2 and poliovirus.²⁰

In another study, the Arizona group showed that L. pneumophila perishes approximately 100 times faster when 0.20 ppm (2 mg/L) of copper and 20 ppm of silver and 0.20 ppm of chlorine were added to the system, compared to the use of chlorine alone. Likewise, the combination of metal ions and chlorine is more effective than the metal ions alone.²¹ Thus, for maximum effectiveness, the use of copper-silver ionizers should be combined with chlorination.

Most Important Uses

The three major areas where copper has been used to stem nosocomial infections include the sanitation of the water supply, of air-conditioning systems, and of surfaces. The CDC addresses copper’s use in two of these, water supplies and surfaces, in its draft guidelines.

Sanitation of the Water Supply

Healthcare facilities use large quantities of water. Because the water is provided by a local utility, it is commonly assumed that it meets all regulatory purity requirements and, therefore, is safe to use.²² Unfortunately, many aquatic microorganisms can and do survive — and even flourish — in municipal water and can be transferred to vulnerable hospital patients directly, i.e., through inhalation, ingestion, surface absorption and, indirectly, via contaminated instruments and utensils. Many outbreaks of infection occur through lack of preventive measures and ignorance of the source and transmission of opportunistic pathogens.²³

While such pathogens as Escherichia coli and Clostridium perfringens are commonly used as surrogate markers, other pathogens such as Cryptosporidium parvum and L. pneumophila can slip by the water authority's quality control measures. In 1993, for example, about 400,000 people in Milwaukee and parts of Illinois became ill from water that held Cryptosporidium, a tiny parasite. Since then, water authorities have paid particular attention to this pathogen.

On the other hand, and despite the 100,000 cases of Legionnaires’ disease that arise in the United States each year, there are no regulatory requirements for the control of L. pneumophila, (the causative pathogen) in water supplies, here or elsewhere. In fact, some current water treatment methods are ineffective in controlling this particular pathogen.

Legionnaire’s disease is especially devastating in healthcare settings, since it predominantly affects individuals with depressed immune systems. In fact, hospital-acquired Legionnaires’ disease has become an international public health issue. Studies of hospitals in Canada, the United Kingdom and the United States indicate that L. pneumophila colonization of water distribution systems ranged from 12% to 100% of those examined.²⁴

Legionellosis was not necessarily observed in all infected hospitals, since the presence of the bacterium alone is not sufficient to cause the disease. Other necessary factors include the presence of a biofilm (inside piping systems or on neglected cooling towers, for example) in which the bacterium can multiply and a means by which the bacterium can become airborne in aerosol droplets of a size fine enough to penetrate deep enough into the lungs to cause infection. Improperly maintained HVAC systems and showerheads perform that function easily.

The number of cases (and deaths) of nosocomial Legionnaires’ disease is not known, but the potential hazard definitely exists, since it has been found that if L. pneumophila is sought in an institution’s water supply, it will be found.²⁵

There has been a continual progression of hospital and nursing home outbreaks and deaths due to Legionnaires’ disease since the illness was first identified in 1976, yet little has been done to prevent its occurrence. For example:

• Diagnosis of seven cases of Legionnaires’ disease resulting in two deaths in the first 9 months of 1996 in an unnamed U.S. hospital led to recognition of a nosocomial outbreak that may have begun as early as 1979. Review of charts from 1987 through September 1996 identified 25 culture-confirmed cases of nosocomial or possibly nosocomial Legionnaires’ disease, including 18 in bone marrow and heart transplant patients. Twelve patients (48%) died. During the first 9 months of 1996, the attack rate was 6% among cardiac and bone marrow transplant patients.²⁶
• In May 2002, two patients contracted Legionnaires’ disease at The Foundation Hospital of Calahorra, Spain.
• In June 2002, ten cases, one fatal, were recorded at an eldercare facility in Horsham, Pennsylvania
• In July 2002, 16 cases, two fatal, occurred in a hospital in Meaux, France, and there were seven nonfatal cases at a hospital in Sarlat, France.
• Also in July 2002, two patients died (out of nine cases) at Los Angeles’ Good Samaritan Hospital.

Unfortunately, little has been done to prevent the occurrence of the disease. Most institutions simply prefer to treat the disease once it arises in spite of the fact that up to 40 percent of the people who contract the disease will die from it. The CDC estimates that 40 percent of those who acquire nosocomial Legionnaires’ disease in a hospital will die from the disease, while only 20 percent of those who acquire the disease outside of a hospital will die. Some outbreaks have claimed more that 50 percent of infected patients.

Preventing Legionnaire's Disease with Copper

Five strategies have been used to control L. pneumophila contagion in healthcare facility water systems.²⁷ One of these — perhaps the most effective, long-term — involves the use of copper:

• Heat and Flush. Hot water (158ºF / 70ºC at the tap) is run through the system for at least 30 minutes. Care is taken to ensure that all outlets are flushed.
• Hyperchlorination. The potable water system is flushed with water containing high concentrations of chlorine (0.5–3.0 ppm / 0.5–3.0 mg/L).
• Ultraviolet Radiation. An ultraviolet sterilizer is installed in the water line (This treatment works only if the system is free from L. pneumophila in advance of installation.)
• Ozonation. Ozone is injected into the potable water yielding a concentration of 1–2 mg/l.
• Copper-silver Ionization. A flow-through ionization chamber containing copper-silver electrodes is installed in the hot-water line. The electrodes slowly dissolve under the action of an impressed electric current. Concentrations of 0.4 ppm of copper and 0.04 ppm of silver have been found to be effective disinfectants with respect to L. pneumophila.

Copper-silver ionizers have been successfully employed to control L. pneumophila in more than 100 hospitals in Canada, Spain, the United Kingdom and the United States. According to Victor L. Yu, M.D. at the Virginia Medical Center and the University of Pittsburgh, copper-silver ionization has displaced hyperchlorination as the long-term disinfection modality of choice.^{28, 29} Both the CDC and OSHA suggest the installation of copper-silver ionizers in healthcare facility water supply systems.^{30, 31} The installation of copper-silver ionizers together with a chlorination system in the Nta Sra del Prado Hospital, in Toledo, Spain, reduced the number of colonized sites from 58.3% to 16.4% after five months of usage.³² In a hospital in which the author was involved in the recommendation of a copper-silver ionization system, it was reported that after six years of operation, there has not been one single case of nosocomial legionellosis. In the seven-year period prior to installation, there had been 38 cases resulting in 11 deaths. (Note: The World Health Organization permits levels of copper in drinking water up to 2 mg/l (2 ppm); whereas, the U.S. Environmental Protection Agency (EPA) permits levels up to 1.3 mg/l (1.3 ppm)).

The use of copper plumbing tube itself can be effective in controlling L. pneumophila as well as other Gram-negative bacteria such as E. coli, Pseudomonas aeruginosa, Acinetobacter calcoacticus, Klebsiella pneumonia and Aeromonas hydrophila.^{33, 34, 35} Copper tube also has been shown to bring about a large reduction in the numbers of poliovirus Type I, Coxsackievirus B2 and rotavirus SA11 in potable water.³⁶

Copper’s Role in Sanitation of Surfaces

Pathogens on microbially contaminated surfaces can become airborne or remain static waiting for contact with staff or patients. Copper fungicides are effective in the control of aspergillosis, an airborne pathogen, in hospitals when used during construction or renovation in areas likely to be subjected to dampness, such as bathrooms. In its draft guideline, the CDC cites the use of copper-base compounds in controlling fungus. Copper-8-quinolinolate was used on surfaces contaminated with Aspergillus spp. in at least one hospital to control an outbreak of aspergillosis.^{37, 38, 39}

The transferal of microorganisms from environmental surfaces via hand contact poses another hazard. While hand washing is important to minimize the impact of this transferal, cleaning and disinfecting environmental surfaces is fundamental in reducing their potential contribution to the incidence of healthcare-associated infections.⁴⁰ The CDC classifies environmental surfaces into medical equipment surfaces (knobs or handles on various instruments, equipment carts, dental units, etc.) and housekeeping surfaces (floors, walls, tabletops, doorknobs, push plates, etc.).

Research has shown that, unlike stainless steel and aluminum, copper and brass doorknobs and push plates are bacteriostatic. Ordinary brass hardware actually hinders the spread of infection. This fact was first brought to light in a hospital setting by Dr. Phyllis J. Kuhn, a bacteriologist at the Hamot Medical Center, Erie, Pennsylvania.⁴¹ In this study, Dr. Kuhn found that newly installed brushed stainless steel doorknobs and push plates were actually less sanitary than the old and tarnished brass fixtures that had recently been removed! Bacteria studied were E. coli, Staphylococcus aureus, Streptococcus Group D and pseudomonas species.

Strips of metal were inoculated with each of these microbes and air-dried for 24 hours at room temperature, inoculated onto blood agar plates and incubated for 24 hours at 98.6ºF (37ºC). According to Dr. Kuhn, the copper and brass showed little or no growth, while the aluminum and stainless steel produced a heavy growth of all microbes. The test was repeated using several drying intervals, from 15 minutes to 24 hours, to determine the kinetics. Brass disinfected itself in seven hours or less depending on the condition of the surface. Freshly scoured brass disinfected itself in one hour. Copper disinfected itself of some microbes within 15 minutes.

On the other hand, aluminum and stainless steel produced heavy growths of all isolates, even eight days after exposure, and growths on all but Pseudomonas after three weeks, when the investigation was ended. Scanning electron microscopy showed that E. coli was completely absent on brass knobs while remaining intact on stainless steel. It also showed that the brushed surface of the stainless steel provided a safe haven for the microbe.⁴²

Additional research demonstrating the effect of copper alloy surfaces on MRSA was performed at the laboratory of Dr. C.W. Keevil at the University of Southampton, U.K.⁴³ The results indicate that the viability of MRSA at room temperature is reduced by seven orders of magnitude to zero in 90 minutes. On a brass, the same reduction is seen in 270 minutes. A copper-nickel-zinc alloy showed a lesser reduction (three orders of magnitude) in six hours, which was the duration of the test. In contrast, no reduction was seen during the six-hour test on the type of stainless steel usually seen in hospitals. These results suggest that the use of copper alloys for door hardware and human-contact surfaces could significantly reduce cross-contamination between staff and patients in hospitals and other healthcare facilities.

In a similar study but one aimed at disinfection in the food industry, Dr. Keevil, found that, at room temperature, it takes 34 days for E. coli O157 bacteria to die on stainless steel tiles, 4 days on brass tiles and just 4 hours on copper tiles.⁴⁴

This work was continued with 25 other copper alloys. In this study, it was shown that the inhibitory effects of a given alloy on E. coli decreases as temperatures decrease from 20°C to 4°C. Furthermore, in general, the inhibitory effects decrease as the copper content of the alloys decreases.⁴⁵ Preliminary results from another phase of the study indicate that copper alloys also inhibit Listeria monocytogenes, another important foodborne bacterium, which threatens human health .⁴⁶

When surfaces are not bacteriostatic, germicides must be used on a regular basis. The tests discussed above suggest that stainless steel doorknobs, push plates, bed rails faucets, stair and corridor handrails, etc. would have to be sanitized as often as every 15 minutes to match the protection provided by naturally bacteriostatic copper and copper alloys.

Sanitizing HVAC Systems

Legionnaires’ disease has largely been associated with the mist distributed from unclean rooftop water-cooled HVAC cooling towers. This mist can affect casual bystanders who happen to be in the vicinity of the building when a gust of wind comes their way from a cooling tower or it can be drawn into the building itself through the ventilation system.

Copper and copper compounds can be used to control the level of bacteria, including L. pneumophila in water-cooled cooling towers and to prevent the development of algae and the biofilms that harbor infestation of L. pneumophila. A number of manufacturers sell copper-silver ionizers for cooling tower use. In addition, various copper herbicides can be used to treat the wooden surfaces in the tower. Also, copper-based antifouling marine coatings can be used on the metal surfaces

Conclusion

For copper and its alloys to become more widely employed to reduce needless hospital infections, their intrinsic antimicrobial advantages must be communicated, recognized and appreciated. Audiences to be informed include:

• Public health officials
• Regulators
• Physicians
• Other healthcare workers
• Patients and the general public
• Hospital administrators and facilities managers
• Hospital infectious disease officers
• Hospital equipment manufacturers
• Hospital designers and materials specifiers
• Hospital construction companies.

Hospitals, the traditional icons of healing, are unfortunately also fertile sources of serious and often fatal infection. Copper, whether used as an antibacterial, fungicidal or viruscidal agent in water treatment systems or simply in the form of plumbing tube and architectural hardware, inhibits the growth of pathogenic organisms. In so doing, it helps reduce the likelihood of nosocomial infection by way of potable water, contaminated surfaces and infectious aerosols. And, importantly, the use of copper alloys offers a methodology to deal with bacterial strains, such as MRSA, that have developed a resistance to commonly used antibiotics. The correct means to engage copper's biostatic properties are well known and amply documented in the peer-reviewed literature. They are also widely available, environmentally benign and cost-effective. All that is needed is the will to apply them .

References

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