Researchers have developed an experimental vaccine that prevents urinary tract infections associated with catheters.
Catheters are tubes used in hospitals and other care facilities to drain urine from a patient's bladder. Each day a catheter is present in the urethra and the bladder, the risk of urinary tract infection increases.
Nearly every patient who has a catheter for more than 30 days acquires a urinary tract infection. The infections make urination painful and can damage the bladder.
If untreated, bacteria can cross into the bloodstream and cause sepsis, a potentially life-threatening complication.
"Catheter-associated urinary tract infections are very common," said first author Ana Lidia Flores-Mireles, a postdoctoral research associate at the School of Medicine at Washington University School of Medicine in St Louis.
"Antibiotic resistance is increasing rapidly in the bacteria that cause these infections, so developing new treatments is a priority," Flores-Mireles said.
Manufacturers typically coat catheters with antibiotics to reduce the risk of infection. But Flores-Mireles and her colleagues found that inserting catheters into the bladder provokes an inflammatory response that results in the catheter being covered with fibrinogen, a blood-clotting protein.
Fibrinogen shields bacteria from the antibiotics and provides bacteria with a landing pad to adhere to and food to consume as they establish an infection, the research found.
"The bacteria use long, thin hairs known as pili to anchor themselves to the fibrinogen, and then they can start to form biofilms, which are slimy coatings on the surface of the catheter composed of many bacteria," said co-author Michael Caparon, professor of molecular microbiology.
"The biofilms protect the bacteria from antibiotics and immune cells, further prevent them from being washed from the body by the flow of urine, and make it possible for bacteria to seed the lining of the bladder with infections," Caparon said.
Working with Enterococcus faecalis, a common cause of catheter-associated urinary tract infections, Flores-Mireles showed that a protein on the end of the pili, EbpA, binds to fibrinogen and makes it possible for the bacteria to begin forming biofilms.
When Flores-Mireles prevented the bacteria from making EbpA, they couldn't start infections.
Next, the researchers injected the mice with a vaccine containing EbpA. The vaccine caused the animal's immune systems to produce antibodies that blocked EbpA and stopped the infectious process.
The scientists are testing to see if the vaccine helps mice clear established infections of E faecalis. They are also working to develop a monoclonal antibody that blocks EbpA to prevent catheter-associated infections in the urinary tract and elsewhere in the body.
The study was published in the journal Science Translational Medicine.
