OBJECTIVE: To determine whether bacteriuria unassociated with symptoms in patients with neurogenic bladder will lead to symptomatic infection and/or deterioration of the upper urinary tract if left untreated, we examined whether bacteriuria persisted in bladder urine of children with neurogenic bladder treated with clean intermittent catheterization (CIC) and whether persistence of bacteria led to symptomatic infection or deterioration of the upper urinary tract. DESIGN: Weekly home visits were made during 6 months of surveillance of 14 children on the CIC regimen with a normal upper urinary tract and no reflux (as determined by renal ultrasonography, voiding cystourethrography, and serum creatinine measurement). During visits a sample of bladder urine was obtained by CIC, and signs and symptoms of urinary tract infection and all medications were recorded. RESULTS: Fourteen children were observed for 323 weeks. Cultures of 70% (172/244) of the urine samples collected were positive for organisms (> or = 10(4) colony-forming units per milliliter), 152 (88%) for the usual pathogens and 20 (12%) for commensal organisms. Bacteriuria was associated with pyuria two thirds of the time, regardless of bacterial species. Carriage of the same pathogen for 4 weeks or longer, with associated pyuria, was common during surveillance. Despite frequent episodes of bacteriuria with associated pyuria, there were only five symptomatic infections during the 323 patient-weeks. Children remained clinically well during the study period, and their upper urinary tract did not deteriorate. CONCLUSION: Bacteriuria persists for weeks in symptom-free children being treated with CIC for neurogenic bladder associated with a normal upper urinary tract. Before attempts are made to eradicate bacteriuria, treatment should be proved to be beneficial to this population.