EVIDENCE-BASED ANSWER
Evidence is insufficient to recommend for or against antibiotic prophylaxis to prevent recurrent urinary tract infections (UTI) in children with anatomic abnormalities. Guidelines acknowledge this lack of evidence, but still recommend using prophylactic antibiotics in children with vesiculoureteral reflux (strength of recommendation: B, based on poor-quality or inconclusive cohort and randomized controlled studies).1-3 No controlled, prospective studies have examined the effectiveness of prophylactic antibiotics to prevent UTI recurrence or renal scarring.
Evidence summary
Recommendations about antibiotic prophylaxis are based on several premises. Reflux predisposes children to acute pyelonephritis; reflux plus infection leads to reflux nephropathy and ultimately to renal scarring. In theory, if antibiotics could be initiated at the appropriate time and be maintained until reflux resolves, we could successfully prevent infection and scarring.4
A recent systematic review evaluated the use of antibiotics to prevent UTI in children.5 This review of 5 randomized controlled trials included a total of 463 children between the ages of 2 months to 16 years. Three out of 5 trials evaluated the effectiveness of antibiotic treatment for 2 to 6 months to prevent subsequent off-treatment recurrence. The 2 smaller trials (n=71) evaluated the use of low-dose long-term antibiotics to prevent UTI.
There was a clinically, but not statistically, significant trend towards reduced risk of UTI during long-term antibiotic treatment (risk reduction [RR]=0.31; 95% confidence interval [CI]=0.10–1.00); however, no sustained benefit was seen once antibiotics were stopped (RR=0.79; 95% CI, 0.61–1.02). There were many problems with the methodological quality of these trials, including significant heterogeneity. The researchers concluded that well-designed randomized controlled trails are still needed to evaluate this commonly used intervention in the pediatric population.4 Benefits for long-term prophylaxis are even less clear in children with low-grade reflux (I–II).5 Furthermore, no randomized controlled trials assess whether prophylaxis prevents the development of new renal scars in children.6
In addition, a recent systematic review of studies done in children with normal urinary tracts, as well in children with neurogenic bladders, found that the available evidence is of low quality. Only 6 out of 31 potential studies fulfilled the inclusion criteria. These were small (mean sample size was 28), and the quality scores of all 6 trials were low, indicating that the evidence may be unreliable.7
Two of 3 studies done in children with normal urinary tracts demonstrated statistically significant higher rates of UTI recurrence in control groups compared with treatment groups receiving 6 to 10 months of either nitrofurantoin or cotrimoxazole (RR=24–31). The third study showed no difference between groups.
One of 2 trials in children with neurogenic bladder demonstrated higher recurrence rates of 2.9 per 10 patient years for patients receiving antibiotics compared with 1.5 in the untreated group. The other study showed lower recurrence rates of 17.1 for patients receiving antibiotics, compared with 33 in the untreated group.7Neither of these findings were statistically significant.
A different meta-analysis of 15 controlled clinical trials in children with neurogenic bladder due to spinal cord dysfunction. This analysis showed that antibiotic prophylaxis was associated with a reduction in asymptomatic bacteruria among children with acute spinal cord injury (P<.05), but there was no significant reduction in symptomatic infections. Prophylaxis resulted in an approximately twofold increase in antimicrobial-resistant bacteria. The researchers concluded that although a clinically important effect has not been excluded, the regular use of antimicrobial prophylaxis for most patients who have neurogenic bladder caused by spinal cord dysfunction is not supported at this time.8