Multiple strategies have been deployed to reduce catheter associated urinary tract infections. These include employing correct hand-washing procedures, avoiding breakages in the urinary collection system and taking measures to prevent commensal bacteria from the patient contaminating the catheter. As well as changes in clinical practice, we need to be mindful of the potential technological and equipment solutions. This article highlights the potential use of silver-alloy urinary catheters to reduce catheter associated urinary tract infections.
by Michelle Beattie
Catheter associated urinary tract infections are often accompanied by an increased period of hospitalisation and morbidity, resulting in poor outcomes for patients as well as their families, and significant economic costs to service providers. Despite the high risk of infection and other potential complications, urinary catheters have many beneficial uses in healthcare including diagnostic, prophylactic and therapeutic uses. Regardless of whether the urinary catheter is used for therapeutic or diagnostic purposes, catheters should only be inserted when deemed absolutely necessary, due to their association with significant morbidity and mortality .
Catheterisation and sources of infection
As urinary catheterisation involves the insertion of a catheter into the bladder via the urethra, the patient is at a higher risk of infection, as essentially the body treats the presence of a catheter as a foreign body. The body’s natural ability to cleanse the urinary tract of micro-organisms is reduced as flushing of the urinary tract by the passage of urine does not occur when a urinary catheter is inserted. A reduction in natural defences increases the risk of micro-organisms. Micro-organisms can enter the bladder through the external (extraluminal) or internal surfaces of the catheter (intraluminal). Commonly, males develop Catheter-Associated Urinary Tract Infection (CAUTI) via the intraluminal route, whereas infection tends to develop via the extraluminal route in females due to the anatomical differences. Micro-organisms can be transmitted by poor hand-washing of healthcare workers, breakages in the urinary collection system and translocation of commensal bacteria from the patient. Bacteria can be free floating or can colonise with the formation of biofilms, which attach themselves to the catheter surface and may subsequently cause catheter blockage. Biofilms are known to have a reduced susceptibility to the actions of antibiotics as resistance develops . Reducing biofilm formation, therefore, is important in reducing CAUTI. Antibiotics are not given as routine prophylaxis due to the risk of antibiotic resistance developing.
Strategies to reduce infection
Multiple strategies continue to be deployed in an attempt to reduce the incidence of catheter associated urinary tract infections, for example, regular hand washing, selecting the most appropriate size of catheter and paying attention to the frequency of catheter bag changes. New technologies and equipment can also support these strategies. In addition there has been much interest in various different materials that can be used to manufacture urinary catheters in an attempt to prevent colonisation; these have been predominantly around the use of antibiotics and, more recently, silver coated surfaces. The use of antibiotic impregnated catheters, however, has been restricted due to the risk of antibiotic resistance developing .
Use of silver
Silver has been used for medicinal purposes since Greek and Roman times. By the early 1900s silver was used for its wide spectrum antimicrobial properties until the discovery of penicillin in 1928. Silver impregnated dressings have been used over the decades to reduce infection in burn wounds. The use of silver-coated urinary catheters was first implemented in the United States approximately 10 years ago and they were introduced into the UK approximately five years ago. The silver-alloy catheter has been designed to be used in the same way as a standard Foley urinary catheter, but is coated with a proprietary silver alloy and hydrogel [Figure 1]. The device is for single use only and recommended for use up to 28 days. The product is thought to function by reducing biofilm formation and/or reducing colonisation of bacteria by releasing silver ions into the urinary tract.
A comparison of silver-alloy and standard catheters
Beattie and Taylor  conducted a systematic review of the literature to determine whether or not silver alloy urinary catheters reduce catheter associated urinary tract infections compared with standard silicone or latex urinary catheters in short term hospitalised adult patients. Randomised control trials, systematic reviews and meta-analyses were identified by searching relevant databases, which resulted in the retrieval of 148 studies. These studies were subjected to various exclusion processes which resulted in 11 papers being retained for analyses. Due to the poor quality of some studies included in other systematic reviews and the inability to carry out meta-analysis of results, definitive conclusions cannot be drawn.
However, the collective evidence did present a consistent pattern favourable towards the efficacy of silver-alloy urinary catheters. This is not to say that the evidence should be dismissed, but rather it should be interpreted with caution.
The use of silver-alloy catheters has been sporadic within clinical practice, probably due to the debatable evidence associated with their effectiveness as well as the significant cost implications. A multi-centre randomised controlled trial is currently underway in the UK, which will provide the definitive evidence required on the effectiveness of these catheters.
Introducing silver-alloy catheters into routine practice
The Department of Health conducted a Rapid Review Panel (RRP), which assesses new and novel technologies and considers their potential for reducing hospital assocaited infections . They found that staff were supportive of the products given that the purpose of implementing changes was to reduce infection. Because the silver-alloy catheter looks and feels the same as a standard Foley catheter, using these devices required little preparation prior to bringing in the change and caused minimal disruption. They reviewed the evidence relating to silver-alloy catheters and concluded that local healthcare organisations needed to balance the clinical benefits with associated financial costs.
Although the results of the review have implications for a multitude of healthcare practitioners and managers, nurses most commonly insert urinary catheters and care for patients post procedure. Given that a quarter of all hospitalised patients will require to be catheterised during their stay, nurses are significantly placed to improve patient outcomes for catheter associated urinary tract infections. These catheters need to be available for those working at the front line before they can be selected for use. Often, silver-coated urinary catheters are not readily available within clinical areas as they have not been purchased for use. Purchasing policies are generally driven on a demand and supply basis, and the demand is likely to increase if there is substantive evidence of their effectiveness. If the use of silver coated urinary catheters became commonplace their availability would increase. A change in practice could reduce catheter associated infection, subsequently reducing the length of time patients stay in hospital as well as long term patient outcomes, which will ultimately improve patient care. Organisations would need to conduct a cost benefit analysis to determine whether the introduction of these products is feasible.
Given that 12-40% (depending on speciality) of hospitalised patients will be catheterised , changing practice to the use of silver-alloy catheters would have a significant impact on patient care. Silver-alloy catheters may well offer an additional strategy to improve infection rates in patients. The potential use of silver-alloy catheters should not detract attention from the importance of basic catheter care to reduce CAUTI, such as considering whether the urinary catheter is essential and removing it at the earliest opportunity.
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3. Beattie M, Taylor J. Silver alloy versus uncoated urinary catheters: a systematic review of the literature. Journal of Clinical Nursing 2011; Available online authorservices.wiley.com/bauthor/onlineLibraryTPS.asp
4. Department of Health. The Results: Using Technology to Fight Infection; Bardex® I.C. silver alloy and hydrogel-coated catheter, May 2009; Available online
5. National Health Service QIS. Healthcare Associated Infection (HAI), Infection Control in NHS Scotland; National Overview, May 2005.
School of Nursing, Midwifery and Health
University of Stirling