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By Sandra K. Watson, RN, BSN, CIC; Deborah Ann Lichtenberg, RN, BSN, CIC; and HollyWainwright, RN, BSN, MBA, CIC
As most hospital infection control programs begin their fifth decade of existence, therising acuity of patients has more than offset gains in lowering the rate ofhospital-acquired infections. In the last 20 years, the rate of noscomial infections hasincreased 36% to 9.8 infections per 1000 patient days.1 Except for thewidespread adoption of the closed system, no new behavioral interventions have been shownto have an enduring effect on the prevention of the most frequently occurring nosocomialinfections--urinary tract infections (UTIs). For decades, experts have tried to developreliable and proven technologies to reduce the incidence of UTIs with limitedsuccess--until very recently. Today, several technological advancements in surfacecoatings on the indwelling, or Foley, catheter have been studied and have been found toreduce the occurrence of nosocomial UTIs. In the current healthcare environment, whichemphasizes cost benefit and cost avoidance, infection control professionals are challengedto improve clinical outcomes such as catheter-associated UTIs (CAUTIs) while conservingresources. Evaluating new technology may help clinicians to meet this challenge. Thissentiment is expressed by one of the nation's foremost infection control authorities,Robert A.Weinstein, MD, who notes, " Given the choice of improving technology orimproving human behavior, technology is the better choice."2
CAUTIs contribute to antibiotic resistance, delay a patient's recovery, and increasehealthcare costs. According to the Centers for Disease Control and Prevention, UTIs arethe most commonly reported nosocomial infection in the US, accounting for approximately40% of all hospital infections. Nosocomial UTIs (NUTIs) cost the nation's hospitals $1.8billion annually.3 Foley catheter use is associated with 80% to 90% of thesehospital-acquired infections.4 NUTIs are also noted to be the second mostcommon infection in critical care units.5
At the 4th Decennial International Conference on Nosocomial and Healthcare-AssociatedInfections, held in Atlanta in March 2000, Dennis Maki, MD, one of the world's mostrespected infection control researchers, noted that 25% to 40% of patients in any givenhospital have a urinary catheter and about 15% to 50% of those patients will develop a UTIas a result of that catheter.4,6 Maki stated that the urinary tract is a sourceof VRE, resistant gram negatives, and yeast, which can easily be transmitted from patientto patient. "I don't think there's any larger reservoir of antibiotic resistantorganisms in hospitals," stated Maki.4
Length of stay for patients with NUTIs may be increased from 1 to 3.8 days. Per casecosts may range from $676, a minimum estimate for a symptomatic but uncomplicated UTI, toan average of $3,803 based on a case control study that determined attributable costdifferences.7,8,9
The indwelling urinary catheter, or Foley catheter, disrupts the normal defensemechanisms of the body. The Foley catheter is a conduit into the bladder and provides anopen and continuous route for bacteria to ascend along the walls of both the internal andexternal surfaces of the catheter.10 Additionally, the retention balloonprevents complete emptying of the bladder, resulting in a small amount of residual urinein which microorganisms can multiply and increase the chance of infection.
The surface of the catheter plays an important role in the development of CAUTIs.Bacteria that colonize both the inner and outer surfaces of the catheter grow inmicrocolonies within a biofilm.10 Once this biofilm has been established, itwill then migrate in all directions along the catheter surfaces.11 The bacteriawithin this biofilm are protected from the activity of antibiotics, making treatmentdifficult. In a recent presentation made to the 4th Decennial International Conference onNosocomial and Healthcare-Associated Infections, Maki stated, ". . . anti-infectivesurfaces, hold the greatest promise for materially reducing the risk of infection withindwelling catheters." 6
The first latex catheter was developed in 1929 by Dr. Frederick E. B. Foley(1891-1966). It was a soft, rubber catheter used to control hemorrhage followingtransurethral prostatectomies.12 Latex was an obvious choice for cathetermaterial due to its durability and properties of strength, flexibility, and elasticity.Originally, latex catheters received a surface treatment with chlorination to help themappear and feel smoother.
In the 1960s, TeflonÂ®-coated latex catheters were developed. These catheters improvedease of insertion and comfort for the patient. They also increased the length of time thecatheter could provide continuous drainage of urine without encrustation. In the 1970s, a100% silicone catheter was introduced with the intention that it would be less irritatingto the bladder and urethra and would inhibit encrustations. Silicone catheters tend tohave thinner walls and slightly larger lumens to allow for better drainage of urine. Theyare also stiffer than a latex catheter and exert a static charge that attracts debris.These catheters are typically more expensive than latex catheters and tend not to providethe average patient with any added benefits. Furthermore, all-silicone catheters are verysusceptible to rapid bacterial colonization and migration (Figures 1 and 2).
To overcome the expense and stiffness of an all-silicone Foley catheter, a siliconeelastomer-coated latex catheter was released that incorporated the flexibility andstrength of latex and the durability and reduced encrustrations typical of 100% siliconecatheters.11 Catheters made of Teflon-coated latex and siliconeelastomer-coated latex were introduced with the hopes of improving compatibility betweenpatient and catheter, but there has been little evidence to demonstrate that lessirritation and inflammation in the urethra occurred with these catheters over thoseconstructed of uncoated latex.13
In the 1980's, hydrogel coatings were introduced to reduce bacterial adherence to thecatheter surface and to reduce the coefficient of friction between the catheter surfaceand the urethral mucosa.14 Hydrogel acts to form a "hydrated cushion"that attracts water to the surface of the catheter and helps it to "float"within the walls of the urethra. This mechanism results in easier insertion and lesspotential for irritation and infection.
The most recent developments with Foley catheter surfaces center on the application ofantimicrobial or antiseptic coatings. The first attempt at an antimicrobial coatinginvolved the use of a silver compound. Silver has a long history in the field of medicineand has been studied in many forms and applications. It is one the first metals known toposses antimicrobial properties at low concentrations and has a low incidence of bacterialresistance. In the late 1980s, a silver compound in the form of silver oxide was appliedto the external surface of Foley catheters. Riley reported in a large randomized trialthat the silver-oxide coated Foley catheter failed to demonstrate efficacy in theprevention of catheter-associated bacteruria.15 Additionally, the coating wasreported to come off and left the patient with a discoloration around the meatal andperineal area. This catheter is no longer manufactured.
A unique technology, developed in 1994, employs the use of silver alloy to coat bothlatex and silicone urinary catheters. These catheters contain a thin monolayer ofcolloidal silver, which is applied to both the inner and outer surfaces of the catheterand is then coated with a permanent layer of hydrogel. The thin layer of silver creates aneffective mechanism for the release of silver ions that are known to be toxic to bacteria.14The colloidal silver inhibits the ability of bacteria to attach, multiply, and migrate oncatheter surfaces decreasing the risk of infection.The hydrogel coatingreduces urethral trauma and helps preserve the natural infection fighting mechanisms ofthe urethral mucosa. The advantages of combining silver alloy and hydrogel include thelack of microbial resistance to colloidal silver and biocompatibility in both adults andchildren.11 Silver and hydrogel coating technology has also been applied to anall-silicone catheter to offer an antimicrobial Foley catheter option for those patientsfor whom a latex-based catheter may be contraindicated.
Many trials have been conducted showing that silver alloy-coated catheters aresignificantly more effective in reducing UTIs than other types of coated and uncoatedcatheters. A meta-analysis by Saint of eight clinical trails demonstrated that silveralloy-coated indwelling catheters were significantly less likely to be associated with thedevelopment of bacteriuria than non-silver alloy-coated catheters. In a separate economicanalysis of the silver alloy-coated catheter, Saint concluded that although the silveralloy-coated catheters cost more than a standard catheter, it saved more than it cost byreducing the costs of nosocomial catheter-related infection and bacteremia.17Saint's meta-analysis associated the use of silver alloy catheters with a 45% reduction inthe incidence of symptomatic UTI and 51% relative decrease in the incidence of bacteremia.The conclusion made by Saint was that consideration should be given to the use of silveralloy-coated catheters in hospitalized patients requiring catheterization for 3-7 days.18
Lettau et. al. conducted a study of the silver alloy-coated Foley catheter innine community-based hospitals. Lettau determined the rate of NUTIs over a six-monthperiod of time, resulting in a 55% decrease in the incidence of UTI with use of the silveralloy-coated catheter. It was concluded that individuals hospitalized for short-term staysrepresented the patient population that could best take advantage of silver alloy-coatedcatheters to prevent UTIs.19
In one of the largest device trials conducted to date, Maki and colleagues found in arandomized, double-blind study involving over 850 catheterized patients that the silveralloy-coated catheters provided substantial protection against CAUTI for up to 20 dayswith approximately 30% reduction in risk. They concluded that the greatest benefit was forpreventing CAUTI caused by gram positive organisms and yeast. The catheter was welltolerated by patients with no attributable side effects or complications. It did notselect for CAUTI caused by silver resistant bacteria and was shown to be cost beneficial.6
Recently, a novel, all-silicone Foley catheter, coated with an antimicrobial drug, wasreleased. This catheter is designed to block bacterial entry along the catheter-urethralinterface and incorporates the antimicrobial agent Nitrofurazone. Nitrofurazone is broadlyactive against many gram positive and gram negative bacteria and has been used extensivelyin medicine. The initial results of the clinical trials showed that the catheter was welltolerated by adult patients and provided quantifiable surface activity for up to sevendays. Maki, et. al., studied this product in a randomized, investigator-blindedtrial of 344 catheterized patients and found a decrease in UTIs within the first sevendays of catheter use. After seven days of use, the catheter did not appear to provideprotection and was not effective for long-term catheterization. It was also noted that theNitrofurazone coated catheter failed to provide a statistically significant reduction ininfections caused by Candida, Enterococcus, or other Nitrofurazone-resistantorganisms.20 Another limited study of 30 burn patients found a reduction inUTIs. However, the incidence of Candida albicans increased three-fold.21Some members of the medical community have expressed their concern that the use of drugcompounds on devices may contribute to the development of antimicrobial resistance due tothe continuous prophylactic release of antibiotics. Healthcare professionals must employdiscretion with the use of Nitrofurazone-coated Foley catheters because of precautionsconcerning their use in children, pregnant women, nursing mothers, and individuals withsensitivity to nitrofurazone (1.2 % of patients treated with topically administeredNitrofurazone exhibit sensitization and generalized allergic reaction).22
There continues to be ongoing research and development aimed at surface technologies ofcatheters. Some new coatings being investigated include conductive polymers and metals tocreate a controlled electrochemical release of silver ions.23 Another method todeter the adherence of bacteria to the catheter surface uses the polysaccharide,hyaluronan due to its lubricious and hydrophilic properities.24 Other coatingshave also included salicylic acid and also the antibiotic ciprofloxacin.25
A comprehensive review of the available literature, indicates that technology is thedirection in which medical advancements are being made. In spite of the dramatic advancesoffered by currently available antimicrobial-coated Foley catheters, there remainsconsiderable opportunity to further reduce the incidence of NUTIs. In a recentpresentation, Maki stated that progress is finally being made in what he thinks is themost challenging device-related infection there is.6
As the twenty-first century unfolds, the challenge to healthcare researchers will be tocontinue to develop better methods to prevent UTIs. In the new millennium, infectioncontrol practitioners must continue to seek multiple approaches that are directed towardaugmenting "technique" with "technology" to improve clinical outcomes.Lastly, infection control practitioners must recognize the impact that their initiativescan make toward reducing the economic pressure of today's healthcare arena by followingthe guidance of Saint who stated, "Given the clinical and economic burden of urinarycatheter-related infection, infection control professionals and hospital epidemiologistsshould use the latest infection control principles and technology to reduce this commoncomplication".
Sandra K. Watson, RN, BSN, CIC is a Infection Control Clinical Specialist, BardMedical Division (Covington, Ga); Deborah Ann Lichtenberg, RN, BSN, CIC, is a InfectionControl Clinical Specialist, Bard Medical Division; and Holly Wainwright, RN, BSN, MBA,CIC, is a Infection Control Clinical Specialist, Bard Medical Division.
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By James Carper
The emergence of multidrug-resistant bacteria is a major concern in hospitals today. Toaddress the problem, infection control professionals are updating and implementingpolicies aimed at both containing the spread of these bacteria and promoting more prudentuse of the antimicrobial agents used to prevent and treat nosocomial infections. One suchinfection, catheter-associated urinary tract infection (CAUTI), has become recognized as amajor reservoir of multidrug-resistant bacteria. Consequently, hospitals are giving anincreased priority to efforts to prevent CAUTIs. Reducing the occurrence of CAUTI causedby multidrug-resistant bacteria also reduces the chance of spreading these types ofinfections. Moreover, when the initial occurrence and spread of bacterial infection arereduced, overall usage of systemic antibiotics can be lowered, thus helping reduce thedevelopment of resistance to those antibiotics.
Among the solutions available for dealing with this problem are technologicallyadvanced products that have been shown to reduce the incidence of CAUTI significantly.Ideally, such new products will reduce the incidence of these infections, reduce usage ofsystemic antibiotics, and allow integration into hospital care without major interruptionsto accepted practices. One product that is proving to meet all these requirements is theRelease-NFÂ® controlled-release nitrofurazone Foley catheter manufactured by RochesterMedical Corporation. Designed to reduce catheter-associated bacterial urinary tractinfections, this catheter has more recently been shown to have a high level of in vitroactivity against many of the types of multidrug-resistant bacteria that are associatedwith hospital-acquired urinary tract infections, including MRSA.1
This latex-free Foley catheter is active against a broader range of bacteria thancatheters using silver coating technologies and, unlike other antimicrobial catheters thatare intended to prevent colonization on its surface, the Release-NF catheter delivers theantiseptic nitrofurazone directly to the patient's urethra. Because the nitrofurazone isnot systemically absorbed, the catheter can provide site-specific antibacterialprophylaxis that can be used without concern for interactions with systemic antibiotictreatments.
Will using Release-NF catheters create bacteria that are resistant to nitrofurazone?Nitrofurazone is an antiseptic with over 50 years of proven efficacy. It is achemosynthetic compound whose kill mechanism is different than organically derivedantibiotics. This may account for the lack of acquired resistance over many years of use.The site-specific use of Nitrofurazone provides a means for slowing the possibility ofincreased resistance to the major antibiotics customarily used for treatment ofinfections. It is those drugs, not Nitrofurazone, that are of great concern for thedevelopment of further resistance. Because the Release-NF catheter targets the delivery ofthe antiseptic to a very small area, it will likely reduce total drug usage by reducingthe need to systemically treat CAUTIs. In contrast, each UTI treated with systemicantibiotics fosters ideal conditions for the development of further resistance by exposinglow levels of antibiotic to the bacteria that flourish in the bowel.
The Release-NF catheter has been shown to reduce nosocomial bacterial UTIs. It is usedas a traditional Foley catheter, yet has been shown to be active against many types of MDRbacteria. In the current era of emerging multidrug-antimicrobial resistance, theRelease-NF catheter is a means of combating the important problem of multidrug-resistantbacteria. Its is a well-targeted local antibacterial technology that will help preventCAUTI and likely reduce the usage of systemic antibiotics and their contribution tomultidrug-resistant bacteria problem.
1. Johnson JR et al. Activities of a Nitrofurazone-containing urinary catheter and a silver hydrogel catheter against multidrug-resistant bacteria characteristic of catheter-associated urinary tract infection. Antimicrob Agents Chemother. 1999;43(12): 2990-2995.
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