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

Abstract

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.

Innovations in indwelling urethral catheterisation

“…Indwelling urinary catheters bypass natural host defence mechanisms to provide a direct route for bacterial entry into the bladder and a surface for the development of biofilm. Biofilms are communities of surface‐adherent micro‐organisms, embedded in a self‐generated extracellular matrix . Bacteria sequestered within biofilm are key players in the pathogenesis of CAUTI because they are protected from host immune responses and antimicrobial agents.…”

Pathogen displacement during intermittent catheter insertion: a novel in vitro urethra model

“…Indwelling catheters historically have been plagued by CAUTIs and many of these issues are caused by bacterial biofilms by urease producing pathogens that lead to crystalline biofilm formations, ultimately blocking the catheter and contributing to recurrent infections (Feneley et al 2002(Feneley et al , 2015Norsworthy and Pearson 2017). Numerous studies have been carried out to test new catheter materials, antimicrobials, natural compounds, alternative catheter designs, probiotics and patient care regimes in an effort to reduce or prevent CAUTIs related to indwelling catheters with varying levels of success (Hull et al 2000;Hentzer et al 2002;Stickler et al 2002;Brosnahan et al 2004;Mathur et al 2006;Stickler 2014;Levering et al 2016;Cortese et al 2018). There are several in vitro models to test the efficacy of indwelling catheters to prevent either biofilm formation, encrustation or CAUTI development (Stickler et al 1987;King et al 1992;Morris et al 1997;Stickler et al 1999;Gaonkar et al 2003;Barford et al 2008;Williams and Stickler 2008;Coenye and Nelis 2010;Jordan et al 2015;Chua et al 2017;Rosenblatt et al 2017;Cortese et al 2018).…”

“…This lower risk of serious complications may be a contributory factor in the relative stagnation in intermittent catheter research and innovation when compared to that of indwelling catheters (Cortese et al 2018). CAUTI prevention for intermittent catheters, traditionally and currently, focuses on preventing the movement of bacteria into the urethra and ultimately the bladder, or preventing pathogens coming into contact with the catheter by utilizing closed 'no touch' systems (Woodward and Rew 2003;Hudson and Murahata 2005;Van Achterberg et al 2008;Holland and Fish 2012;Cortese et al 2018;Goetz et al 2018). The idea that a CAUTI can be initiated by insertion of a single catheter with a contaminated tip was first proposed by Kaye et al (1962) and is supported by the more recent research of Barford et al (2008).…”

A novel in vitro urethra model to demonstrate bacterial displacement during urinary catheter insertion

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Coates, "A model of catheter-associated urinary tract infection initiated by bacterial contamination of the catheter tip,"Catheter associated-urinary tract infections (CAUTIs) are one of the most common hospital-acquired infections [1]. There is currently no standard established in vitro urethral model to test the efficacy of intermittent catheters designed to prevent/control introduction of bacteria into the urethra and bladder [2]. It was the aim of this study to address this issue by the development of a reproducible in vitro agar based urethral model and to evaluate the hypothesis that insertion of a urinary catheter can push bacteria from the urethral meatus up the urethra channel.

AcknowledgementsFunding for this project was provided by the Athlone Institute of Technology President Seed Fund and a collaborative industry partnership with Teleflex.The in vitro urethra model described in this study has been validated through 12 independent tests with 2 bacterial species to ensure the reproducibility of the model and methodology, and versatility with both Gram positive and negative species.

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“…Catheter associated-urinary tract infections (CAUTIs) are one of the most common hospital-acquired infections [1]. There is currently no standard established in vitro urethral model to test the efficacy of intermittent catheters designed to prevent/control introduction of bacteria into the urethra and bladder [2]. It was the aim of this study to address this issue by the development of a reproducible in vitro agar based urethral model and to evaluate the hypothesis that insertion of a urinary catheter can push bacteria from the urethral meatus up the urethra channel.…”