A new infection alert system in catheters could prevent serious infections in millions of hospital patients worldwide. The system, detailed in a new paper in “Biosensors and Bioelectronics,” changes the color of the urine so patients and healthcare providers can see easily if bacteria are starting to block the catheter.

Designed by Dr. Toby Jenkins and his colleagues at the University of Bath, the new catheter infection alert system provides a means of early detection, so the catheter can be changed and the infection treated before a person becomes unwell. “Catheter-related infections are a serious problem, especially if the bacteria are resistant to antibiotics,” said Jenkins. “We hope that with this simple-to-use sensor system we can ultimately make a real difference to patients' lives.”

Over time bacteria can build a layer called a biofilm inside the catheter tubes that eventually blocks them. The urine can't escape and pushes back into the kidneys where the bacteria can cause kidney failure, body-wide infection and death. Up to half of people who use catheters long-term have problems with blockages caused by bacteria, but there is currently no way to detect potential blockages before they cause problems.

The new coating detects biofilms built by a bacterium called Proteus mirabilis, the most common cause of catheter blockage. The system gives advanced warning of a catheter blockage 10 to 12 hours before it happens. The coating is made up of two layers. The first reacts to changes in urine caused by the bacteria; the second layer releases the dye. The dyed urine gathers in the collection bag, turning the urine bright yellow. The color change reveals the infection.

Biofilms built by bacteria are not easy to treat. They avoid the natural defenses of the immune system and can't be broken down by antibiotics. Jenkins is optimistic about the benefits of the system: "Our new coating works with existing catheter designs and gives a clear, early visual warning of infection before a catheter is blocked. It could dramatically reduce the number of infections resulting from bacterial blockages."