Antimicrobial prophylaxis does not reduce the risk of recurrent UTIs in children—but does increase the risk of antibiotic resistance, new data show.Researchers at the University of Pennsylvania in Philadelphia followed 611 children age 6 and under who were diagnosed with a first UTI between July 1, 2001, and May 31, 2006. Most of the children (543) with first UTI were female.The children who particpated in the study were drawn from a network of 27 primary-care pediatric practices in New Jersey, Delaware, and Pennsylvania.The researchers’ goal was to identify risk factors for recurrent UTI in children, determine the association between antimicrobial prophylaxis and recurrent UTI, and identify risk factors for antibiotic resistance.

Of the children diagnosed with a first UTI, 83 (13.6%) developed a recurrent UTI, defined as a second positive urine culture two or more weeks after therapy for the first UTI. Fully 61% of these recurrent UTIs were caused by a pathogen with antimicrobial resistance—mostly (78%) Escherichia coli.

Several factors were associated with an increased risk for recurrent UTI. They included white race and being between the ages of 3 and 5, both of which doubled the risk. Having grade 4 or grade 5 vesicoureteral reflux increased the risk more than four times. In addition, the risk for antimicrobial resistance among children with recurrent UTI was increased more than sevenfold.

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The authors note that race may also play a role in risk of recurrent UTIs and resistant infections. “Nonwhites had a decreased risk of recurrent UTI, yet an increased risk of resistant infections,” they write. “All nine recurrent UTIs in nonwhites exposed to prophylactic antimicrobials were caused by a resistant organism” (JAMA. 2007; 298:179-186).