Antibiotics don't prevent future urinary tract infections in children.

After a first childhood urinary tract infection (UTI), daily antibiotics may not prevent another such infection, and may actually increase the risk that the next urinary tract infection is caused by resistant bacteria, according to a new study in the July 11 issue of the "Journal of the American Medical Association."

In the first large study of children diagnosed with UTI in a primary care pediatric setting, researchers from The Children's Hospital of Philadelphia reviewed the electronic health records of 74,974 children with at least two clinic visits in the hospital's pediatric health care network between July 2001 and May 2006. The researchers found that 611 children had a first urinary tract infection and 83 had a recurrent UTI. Children between ages 3 and 5, Caucasians, and those with severe vesicoureteral reflux had the highest risk of recurrent UTI. Receiving a daily dose of preventive antibiotics was not associated with a lower risk of recurrent UTI.

"The majority of children with first UTI were female, Caucasian and 2 through 6 years old. Most did not have an imaging study performed and did not receive daily antibiotics to prevent infections," said Patrick Conway, M.D., primary investigator of the study, in a statement released by the hospital. "We found that daily antibiotic treatment was not associated with a decreased risk of recurrent UTIs, but was associated with an increased risk of resistant infections."

'More definitive studies, such as clinical trials, are needed to look at this issue,' said Ron Keren, M.D., a general pediatrician at The Children's Hospital of Philadelphia and senior author on this study. "But given these findings, it is appropriate for pediatricians to discuss with families the risks and unclear benefits of daily preventive antibiotic treatment after a child has had a first UTI."

UTIs are common in children. In fact, of all the children born in one year, 70,000 to 180,000 will have a UTI by age six.

The American Academy of Pediatrics practice guideline for management of children after a first UTI recommends an imaging study to evaluate the presence and degree of vesicoureteral reflux (VUR), a condition found in approximately 30% to 40% of children who have had a UTI. If the child has VUR, daily antibiotic treatment is recommended in an attempt to prevent recurrent UTIs.

Vesicoureteral reflux (VUR) occurs when urine in the bladder flows back into the ureters or kidneys during urination. It is thought that a child who has VUR is at risk for developing recurrent kidney infections, which, over time, can cause damage to the kidneys. However, Conway summarized, "The majority of children have lower grade VUR and this lower grade VUR was not associated with an increased risk of recurrent UTI in our study."