New Infection Alert in Catheters Could Tackle Hospital “Superbugs”

System detects bacterial biofilms

A new infection alert system in catheters could prevent serious infections in millions of hospital patients worldwide, according to a paper published in Biosensors and Bioelectronics. The system changes the color of the urine so caregivers and patients can see whether bacteria are starting to block the catheter.

The system was invented by researchers at the University of Bath in the United Kingdom, who say it could help tackle hospital-acquired urinary infections. It could also be beneficial for elderly people in care homes.

An estimated 100 million urinary catheters are used around the world every year, and the infections they sometimes cause can be problematic for thousands of people, the researchers say. Hospital-acquired urinary infections occur in more than 90,000 patients each year in the United States, according to the Centers for Disease Control and Prevention.

“Catheter-related infections are a serious problem, especially if the bacteria are resistant to antibiotics. We hope that with this simple-to-use sensor system we can ultimately make a real difference to patients’ lives,” said lead researcher Dr. Toby Jenkins.

Over time, bacteria can build a layer called a biofilm inside catheter tubes, and this layer can eventually block the tubes. The urine can’t escape and pushes back into the kidneys, where the bacteria can cause kidney failure, systemic 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.

In the new alert system, a coating detects biofilms built by a bacterium Proteus mirabilis, the most common cause of catheter blockage. The system gives advanced warning of a blockage 10 to 12 hours before it happens.

The coating is made up of two layers. The first layer reacts to changes in urine caused by the bacteria, and the second layer releases a dye. The dyed urine gathers in the collection bag, turning the urine bright yellow. This color change reveals the presence of infection.

Jenkins’ team used a glass bladder, artificial urine, and bacteria from patient samples to test the system, which responds to changes in the acidity (pH) of urine caused by bacteria. As bacteria multiply, the substances they release raise the pH so that the urine becomes more alkaline than acidic. This change dissolves the top layer of the coating, releasing the bright dye held in the second layer.

The tests with the glass bladder showed that when there is no bacterial infection, the dye stays in the second layer despite liquid constantly flowing past it.

Biofilms built by bacteria are not easy to fight, Jenkins said. They avoid the natural defenses of the immune system and can’t be broken down by antibiotics. Jenkins is optimistic about the benefits of his team’s alert 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.”

Source: Medical Xpress; April 22, 2016.