The immune systems response to urinary tract infection may have a bearing on the risk of recurrence – an overactive immune response appears to increase the risk, say researchers at Washington University School of Medicine in St. Louis. Their study is published in the medical journal PLOS Pathogens.

The scientists used a mouse model to demonstrate that severe inflammatory responses to initial urinary tract infection (UTI) may cause damage to the bladder, resulting in longer-lasting infection. They also found that immunodeficient mice – mice with weak immune systems – that did not have these severe inflammatory responses were much less likely to suffer from chronic (long-term, recurring) bladder infection.

They also demonstrated that mice with a history of chronic bladder infection that was subsequently cured with antibiotic treatment develop persistent immune cell infiltrations within the bladder wall, and these mice are highly susceptible to further UTI.

Lead author Thomas J. Hannan, DVM, PhD., said:

We found markers in the mice that may one day help us identify patients vulnerable to recurrent infection and refine our treatment strategies. There were infection-fighting elements in the responses of some mice that we might, for example, be able to promote through vaccines for these patients.

Millions of people suffer from urinary tract infections annually. While treatment with antibiotics has been effective, antibiotic resistance is an increasingly growing concern, according to Scott Hultgren, PhD, director of the Center for Women’s Infectious Diseases Research, where the experiments were conducted.

Hultgren said:

Women and infants are at greatest risk for having a UTI, and chronic and recurrent infections are common. UTIs are estimated to cause around $1.6 billion in medical expenses every year in the United States.

Researchers at Hultgren’s laboratory are now collaborating with scientists at the University of Washington and Duke University to determine whether the mouse results can lead them to markers of vulnerability to recurrent infection in humans.

“Early Severe Inflammatory Responses to Uropathogenic E. coli Predispose to Chronic and Recurrent Urinary Tract Infection”
Thomas J. Hannan, Indira U. Mysorekar, Chia S. Hung, Megan L. Isaacson-Schmid, Scott J. Hultgren
PLoS Pathog 6(8): e1001042. doi:10.1371/journal.ppat.1001042

Written by Christian Nordqvist