There is recent conflicting evidence regarding the benefit of antimicrobial prophylaxis. In a meta-analysis of eight randomized controlled trials that included 677 children who had recovered from a symptomatic UTI and in whom vesicoureteral reflux had been identified independent of acute infection, there was no difference between those who did and did not receive antimicrobial prophylaxis in recurrence of symptomatic UTI or in the incidence of new or progressive renal scarring (Acta Paediatr. 2009;98:1781-6).
But the 20-center Swedish Reflux Trial did find benefit. In that study, reflux status was compared in 203 children (128 girls/75 boys) with grade III-IV dilating vesicoureteral reflux who were treated in one of three groups, either with low- dose antibiotic prophylaxis, endoscopic therapy, or with surveillance and antibiotic treatment only for febrile UTI. At 2 years, reflux had improved in all treatment arms, with reflux resolution or downgrading to grades I or II occurring in 39% of the prophylaxis group, 71% with endoscopic treatment, and 47% with surveillance (J. Urol. 2010;184:280-5).
Of concern, however, dilating reflux reappeared after initially being downgraded in 20% of the children who had received endoscopic treatment.
Both antimicrobial treatment and endoscopic therapy reduced the infection recurrence rate among the girls, occurring in 8 of 43 (19%) on prophylaxis and 10 of 43 (23%) with endoscopic therapy, compared with 24 of 42 (57%) on surveillance. In girls, the recurrence rate was associated with persistent reflux after 2 years. However, reflux severity (grade III or IV) at study entry did not predict recurrence (J. Urol. 2010;184:286-91).
Given the conflicting data, it's no surprise that guidelines also differ. The AAP advises ultrasound and VCUG for all children aged 2 months to 2 years, and antimicrobial prophylaxis for all in whom reflux is identified (Pediatrics 103;1999:843-52). In contrast, guidelines from the United Kingdom advise ultrasound only for recurrent or “atypical” UTI, and do not recommend prophylaxis after a first UTI, but only after a recurrence.
Also not surprising, practitioners differ in what they do. In an analysis of Washington State Medicaid data for 780 children diagnosed with UTI during their first year of life, less than half received either timely anatomic imaging (44%) or imaging for reflux (39.5%). Of those who had imaging for reflux, only 51% had adequate antibiotics to maintain antimicrobial prophylaxis between diagnosis and imaging for reflux (Pediatrics 2005;115:1474-8).
I believe there is certainly a role for prophylaxis in a child with recurrent UTI, especially recurrent symptomatic/febrile UTI. But whether there's a role after the first UTI remains uncertain, with conflicting evidence. We might get some answers from an ongoing randomized, placebo-controlled intervention sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (clinicaltrials.gov