Studies in mice suggest an overly strong inflammatory reaction to a urinary tract infection may open the door to recurrent infections, U.S. researchers say. Researchers at Washington University School of Medicine in St. Louis find after two weeks of infection, the bladder wall undergoes additional changes that leave mice more vulnerable to later infection. However, these vulnerabilities were decreased if the immune system was depressed during initial infection. "We found markers in the mice that may one day help us identify patients vulnerable to recurrent infection and refine our treatment strategies," lead author Thomas Hannan says in a statement quoted by the United Press International (UPI). "There were infection-fighting elements in the immune responses of some mice that we may, for example, one day be able to trigger with vaccines for vulnerable patients." Hannan and colleagues infected mice with urinary tract infections for a month. Some mice spontaneously resolved their infections; others developed a persistent infection -- high levels of bacteria in the urine and bladder and high levels of inflammation in the urinary tract. After researchers cleared this infection with antibiotics for four weeks, all of the mice were exposed with other urinary tract infection-causing bacteria that they could distinguish from the initial infectious bacteria. The study, published in PLoS Pathogens, finds the mice that had chronic bacterial cystitis in the first round of infection but avoided it in the second had little or no bacteria in their urine during the second test.
