To investigate the risk factors for recurrent urinary tract infections (UTIs) in infants with vesicoureteral reflux (VUR) and whether bacterial pathogen affected breakthrough UTI or not.

We compared children with infantile VUR with recurrent UTI (33 males, 11 females, mean age 3.2 months) and without recurrent UTI (40 males, 7 females, mean age 4.8 months). The following were compared between the 2 groups: sex, timing of UTI episode, bacterial growth on urine culture, degree and bilaterality of the reflux, hydronephrosis, renal scar, and delayed ureteral excretion of refluxed contrast on voiding cystourethrogram (VCUG).

Univariate Cox survival-time regression showed that younger age at first UTI, a non-Escherichia coli strain, bilateral and VUR, high-grade VUR, and hydronephrosis on initial ultrasonography (USG) significantly increased the risks of recurrent UTI (P <.05 each). In multivariate analysis, timing of the UTI episode (P = .015), a non-E. coli strain (P = .003), high grade (P = .012), and bilateral VUR (P = .002) were independently associated with increased risk of recurrent UTI. Non-E. coli strains were identified in 60% and 33% of infants with and without recurrent UTI, respectively.

During the first year of life, the earlier the first UTI then the higher the chance is for recurrent UTIs. Higher grades of reflux, bilateral VUR, and the first infection by a non-E. coli strain all significantly increase the risk of recurrent UTIs.