Selecting The Right Medical Plastics To Combat Hospital-Acquired Infections (HAIs)
By Len Czuba, President, Czuba Enterprises, Inc.
It seems that everyone in healthcare is talking about how hospital-acquired infections — also called healthcare-associated infections, or HAIs — are a growing concern in the industry. Whether the cause is reduced staffing in hospitals (resulting in less time for healthcare workers to thoroughly disinfect between patient visits), the increasing resistance of certain pathogens to current sterilization procedures, or any of a dozen other reasons, this problem continues to affect our customers, i.e., patients needing healthcare.
According to a recent study by the Centers for Disease Control and Prevention, more than 722,000 cases of HAIs were reported in U.S. acute care hospitals in 2011. About 75,000 patients with HAIs died during their hospitalization, the CDC found. In addition, the added cost of treatment for patients who fall ill to HAIs represents a preventable burden to our healthcare system.
If we examine why our industry so readily adopted the use of plastic medical devices when they first were developed, we can see the features that made these products attractive: cleanliness, sterility, convenience, ease of use, and low cost. In and of itself, the use of plastic medical devices helps caregivers to control the HAI problem. But our industry is being asked to do more in controlling and reducing infections, and one way to help improve outcomes is through the use of antimicrobial plastics in the construction of various medical devices.
Antimicrobials Are Effective In Certain Applications
For years, antimicrobial additives have been incorporated into a limited number of medical devices, including urinary (Foley) catheters, wound dressings, and various textile products, such as bedding, surgical garments, and draping. The effectiveness of antimicrobials in preventing infection is related, in part, to the environment in which these products are being used. Catheters and wound dressings, in particular, are used in warm, moist areas of the body where infectious “bugs” can readily grow. In these applications, the antimicrobial is incorporated into the plastic of the device, whose surface interacts with potential pathogens, disrupting their ability to propagate and colonize. The antimicrobial is bound permanently to the device, and it will continue to serve its function — as long as heavy layers of foreign material (e.g., blood, sputum, food, etc.) do not adhere to its surface, isolating microbes from contact with the active antimicrobial.
Some antimicrobials are designed to release from the device surface to better react with pathogens threatening the patient. In these cases, the antimicrobial disrupts the ability of the microbe to propagate and multiply into colonies. The only drawback to this type of antimicrobial is the limited duration of its effectiveness. As the reactive anti-microbial is released from the polymer surface, it reacts with the pathogen , but only so much reagent can be released before the antimicrobial is exhausted and the device no longer is effective in preventing microbial growth. However, an advantage of this type of antimicrobial is that, once released, the reagent can diffuse among the threatening pathogens and prevent colonization. The effects of surface-bound antimicrobials are limited to those pathogens that are in direct contact with the reactive surfaces.
Understand The Limitations Of Antimicrobial Plastics
In both surface-bound and released antimicrobials, the reagent requires some time to be effective. Unlike the almost-instant sterilization that occurs when a disinfecting wipe is used to clean a surface prior to an injection or prepare a surface that will be in contact with tissue or blood, the sterilization provided by antimicrobial plastics is almost never immediate. Thus, it would be irresponsible for any company making antimicrobial products to assure healthcare workers that a poorly cleaned and disinfected injection site is safe simply because it is protected by the antimicrobial in the plastic.
Healthcare providers also must be careful to avoid overuse of antimicrobials. Some may reason that “If there is any chance that antimicrobials could help, then why not use them widely in the the construction of medical devices?” These same supporters would promote putting antimicrobials into tubing, connectors, syringes, and connectors, as well as the wide variety of molded parts being used in healthcare devices.
In addition to the added cost of including these agents in the plastics, I worry that overuse of antimicrobials could promote development of super-strains of new bacteria, and could threaten a product's surroundings after its useful life has ended. Super-strains and drug-resistant bacteria in the healthcare industry have emerged as a worrisome trend that has been linked to the overuse of antibiotic medicines. Standard medicines, due to their reported overuse, are losing their effectiveness against some of these drug-resistant strains.
Another reason to limit the use of antimicrobials is Environmental Protection Agency (EPA) concern regarding antimicrobials in plastics, because the plastic devices usually end up in landfills after use. The EPA is concerned about the antimicrobial leaching from the plastic and contaminating the environment. Since the EPA has not determined what the long-term consequences of that seepage may be, the agency is taking a conservative approach to approving antimicrobials' use.
Select Plastics That Will Survive Cleaning And Disinfection
Proper selection of plastics can provide a significant benefit to HAI prevention when applied to the design and fabrication of medical products. Durable goods, such as instrument housings, laptop and notebook screens and keyboards, equipment handles, furniture, and reusable device parts, represent surfaces that will be increasingly challenged by more aggressive cleaning solutions, disinfectants, and cleaning procedures. The polymers also need to withstand exposure to chlorinated cleaners, various solvents, abrasives, and increased sterilization cycle temperatures.
Polymers that will not craze or crack, discolor, or show any negative effects from repeated cleaning challenges can be considered “antimicrobials,” because they will survive contact with the cleaning procedures that render the surfaces clean and uncontaminated. Improved design also will help control and reduce HAIs, in that all surfaces of a device will be easily accessible for cleaning and sterilization.
A good rule of thumb is “unless the product (or surface) is clean, it cannot be sterile.” I believe an inability to clean every joint and interface, on certain devices, has contributed to the patient exposure to deadly pathogens we have seen in the news recently. Although these instruments were designed to be cleaned, sterilized, and reused, some could not be thoroughly cleaned due to complicated designs and, as a result, could not be completely sterilized. In such cases, it was not the materials of construction that created a problem. The way instruments are designed, built, and assembled allowed pathogens to infiltrate tightly fitted parts, such as hinges and joints. In an attempt to curb this problem, the U.S. Food and Drug Administration (FDA) is investigating recommended cleaning and sterilization procedures used by healthcare institutions, and then advising new or different procedures for these reusable instruments.
Summary
In summary, I believe that polymers and, more specifically, the proper selection of such materials in construction of medical devices, will continue to be a factor in helping control hospital-acquired infections, and will allow our industry to provide better patient safety, improved healthcare, and reduced operating costs.
Whether the improvement comes from surface-bound or released antimicrobials in medical device plastics; from the use of more resistant polymers; or from better design that allows more effective cleaning and longer useful life of the plastic products, the improved outcomes will be a welcome trend. Device engineers, manufacturing companies, and product users will see a reduction in the frequency of HAIs while continuing toward the goal of eliminating them entirely.
About The Author
Len Czuba is the president of Czuba Enterprises, Inc., whose new product development initiatives include taking medical devices from concept to market. Czuba has a BS in biosciences from Southern Illinois University, as well as more than 30 years of experience in polymer synthesis, compounding and material development in the medical device industry. He may be contacted at LCzuba@czubaenterprises.com, or by visiting www.czubaenterprises.com.