New Antimicrobial Catheter Reduces Infection Risk for Dialysis Patients

The polymer silicone material of the catheter is constructed of a network formed from molecules that have tiny spaces in between them; the device is then soaked in a chemical bath containing chloroform, which causes the silicone to swell to twice its normal size, enlarging the spaces between the molecules.

Another series of baths impregnates the silicon with antimicrobial agents. Finally, the chloroform is removed and the device subsequently shrinks back to its normal size, encasing the antimicrobial agents inside the material, but allowing them to move through the silicone and kill any pathogens coming into contact with the surface of the catheter. The catheter has been shown in the lab to kill on contact a wide range of common types of staphylococcal infections, including hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA), and, for the first time, a number of gram negative pathogens, including Escherichia coli. The new catheter is intended to protect continuous ambulatory peritoneal dialysis (CAPD) patients from infections for up to 100 days, around 20 times longer than current catheters. The results of the lab studies were published in the March 14, 2009, issue of Biomaterials.

"This study has not only demonstrated the potential of what this catheter can do but has established the need for rigorous and clinically-focused laboratory evaluation of such new devices," said codeveloper Roger Bayston, Ph.D. "The lab-based studies have already shown such robust results that the likelihood of the catheter demonstrating satisfactory clinical performance is extremely high."

CAPD uses a catheter directly into the patient's peritoneal cavity to collect waste fluids and replace them with dialysis solution, which is left in the body for around five hours and does the work that would normally be done by the kidney. As it is a simple process that can be completed at home, patients can enjoy a relatively normal lifestyle. However, the length of time the catheter needs to be left in the body and its direct insertion into the peritoneal cavity leaves the patient especially vulnerable to infection, which often means the removal of the catheter and a return to traditional hospital-based hemodialysis, which can take up to four hours and needs to be done around three times a week, having a huge impact on the patient's quality of life.

The researchers also hope to adapt the catheter for use in central venous catheters and urinary catheters. This will involve some adaptation to cover specific pathogens such as, in the case of foley catheters, Proteus which produces a biofilm on the catheter and converts urea in urine into ammonia, causing minerals and phosphates to form a painful crystallized crust at the neck of the catheter.

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