Resistance to three or more antibiotics occurs in one in eight patients hospitalized with a severe urinary tract infection, according to a large multicenter retrospective analysis of U.S. hospital data.

Among more than 23,000 patients with complicated UTI, 13% had a triple resistant pathogen infection, reported Andrew F. Shorr, M.D., of Washington Hospital Center, Washington, DC. These patients were more likely to be prescribed a carbapenem, antimicrobials usually reserved for known or suspected multidrug-resistant bacterial infections. But they also were more likely to be overtreated when compared with their peers without triple resistance. This, in turn, worsened clinical outcomes, Shorr and colleagues wrote.

Mortality was similar between the cohorts, but triple resistance added a third of a day to hospital length-of-stay and significantly greater costs. And inappropriate empirical treatment resulted in nearly one more day in the hospital, and excess costs of over $1,300. Notably, both triple resistance and inappropriate empirical treatment impacted patient outcomes whose UTI was non-catheter-associated — but these factors had no effect on outcomes in patients with catheter-associated UTIs, the researchers said.

The findings suggest that clinicians need to be aware of a patient’s prior healthcare and antibiotic exposures when making prescribing decisions, Shorr and team wrote. But the findings are not a call to abandon current practices and begin selecting broader-acting antimicrobials for first-line therapy in complicated UTI. “That would only serve to foster more resistance,” they said. 

Triple resistance was defined as resistance to three or more of the following: Third-generation cephalosporins, fluoroquinolones, trimethoprim-sulfamethoxazole, fosfomycin, and nitrofurantoin. 

The study was published in the journal BMC Infectious Diseases.