Review of Catheter-Associated Urinary Tract Infections and In Vitro Urinary Tract Models

Hindawi Journal of Healthcare Engineering Volume 2018, Article ID 2986742, 16 pages https://doi.org/10.1155/2018/2986742 Review Article Review of Catheter-Associated Urinary Tract Infections and In Vitro Urinary Tract Models Yvonne J. Cortese ,1,2 Victoria E. Wagner,3 Morgan Tierney,3 Declan Devine ,1 and Andrew Fogarty 2 1 Materials Research Institute, Athlone Institute of Technology, Athlone, Ireland Bioscience Research Institute, Athlone Institute of Technology, Athlone, Ireland 3 Teleflex, Reading, PA, USA 2 Correspondence should be addressed to Declan Devine; Received 31 January 2018; Revised 1 June 2018; Accepted 3 July 2018; Published 14 October 2018 Academic Editor: Jui-Yang Lai Copyright © 2018 Yvonne J. Cortese et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Catheter-associated urinary tract infections (CAUTIs) are one of the most common nosocomial infections and can lead to numerous medical complications from the mild catheter encrustation and bladder stones to the severe septicaemia, endotoxic shock, and pyelonephritis. Catheters are one of the most commonly used medical devices in the world and can be characterised as either indwelling (ID) or intermittent catheters (IC). The primary challenges in the use of IDs are biofilm formation and encrustation. ICs are increasingly seen as a solution to the complications caused by IDs as ICs pose no risk of biofilm formation due to their short time in the body and a lower risk of bladder stone formation. Research on IDs has focused on the use of antimicrobial and antibiofilm compounds, while research on ICs has focused on preventing bacteria entering the urinary tract or coming into contact with the catheter. There is an urgent need for in vitro urinary tract models to facilitate faster research and development for CAUTI prevention. There are currently three urinary tract models that test IDs; however, there is only a single very limited model for testing ICs. There is currently no standardised urinary tract model to test the efficacies of ICs. 1. Introduction The urinary system is one of the main routes through which the human body excretes liquid waste. The urinary tract is divided into two sections: the upper tract consists of the kidneys and ureters, where liquid wastes from the body are converted into urine and other products; and the lower tract includes the bladder and urethra, where urine is stored in the bladder before being expelled from the body through the urethra [1]. The outermost section of the urethra and the tissue surrounding the urethral opening are known as the urethral meatus [2]. When functioning normally, the lower urinary tract flushes out the urethra as the bladder empties, preventing the movement of bacteria up from the periurethral skin into the urethra and then into the bladder [3]. If bacteria manage to enter the bladder of a healthy individual, they will usually be expelled during micturition. However, if they remain, the bladder’s internal surface is resistant to bacterial attachment as it is lined with urothelial cells that are covered in a glycosaminoglycan mucin that prevents bacteria adhering to the internal bladder surface [3]. In the event that a bacterium bypasses this first line of defences, the immune system should be able to eliminate the bacteria as long as the patient is healthy. If the immune system fails, a urinary tract infection (UTI) can occur and possibly lead to serious illness [3]. When problems arise in the lower urinary tract such as nerve damage or muscle atrophy leading to incontinence, or by prostate enlargement or urethral stricture resulting in urinary retention, the use of a urinary catheter becomes a necessity [1, 3]. 2 2. Urinary Catheters A urinary catheter is a long tube that can be constructed from any number of different polymers, with silicone being typically used, and latex rubber also common [4]. When required, the urinary catheter is inserted into the urethra as far as needed until the urine begins to flow. This is known as transurethral catheterisation. A catheter can also be inserted by a medical professional through the creation of an artificial track between the bladder and the abdominal wall, known as suprapubic catheterisation [3]. A urinary catheter can be a temporary or long-term solution depending on the patient’s personal mobility and their prognosis. If a patient has the ability to take care of their own medical needs, temporary self-catheterisation can be the best option and performed easily [3]. For patients in which selfcatheterisation is not an option, indwelling catheters become a necessity to maintain proper function of the urinary system. The most commonly used urinary catheter in the world is the Foley catheter that was invented by an American urologist named Frederic Foley [3]. The Foley catheter consists of a tube containing two channels; the larger channel allows the flow of urine from the bladder, and the smaller channel allows inflation of a balloon just below the tip of the catheter that, once inflated, holds the catheter in place until removed (Figure 1). Under optimal conditions, a urinary catheter can stay in place for up to approximately 12 weeks. However, this is often not the case as encrustation and bacterial infection can block the catheter or lead to medical complications [3]. 3. Urinary Tract Infections Catheters are one of the most commonly used medical devices. However, these devices are notoriously prone to infection. Infection is the largest concern with catheter use, whether long term or short term. Catheter-associated urinary tract infections, abbreviated to CAUTIs, are the most commonly faced hospital-acquired infections or nosocomial infections [5, 6]. CAUTIs can lead to numerous medical complications such as catheter encrustation, bladder stones, septicaemia, endotoxic shock, and pyelonephritis [5]. CAUTIs can be caused by yeasts or bacteria, including both Gram-positive and Gram-negative bacteria [4]. A study by Chatterjee et al. [7] sampled 150 catheters from patients with no history of UTIs and found that 130 of the catheters had pathogens present both on the catheter and in accompanying urine samples. The most common microorganisms found during the study by Chatterjee et al. [7] included “Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Escherichia coli, Citrobacter freundii, Providentia rettgeri, and Candida albicans”. These bacteria can cause asymptomatic bacteriuria or UTIs which can be devastating to at-risk patients. All catheter types and brands are vulnerable to CAUTIs, biofilm formation, or encrustation, and current methods to prevent these complications may just delay the process Journal of Healthcare Engineering without treating the proble (...truncated)