LAUSR

Background Few studies have reported on breakthrough urinary tract infection (UTI) associated with the susceptibility of index UTI to prophylactic antibiotics in children with primary vesicoureteral reflux (VUR) receiving continuous antibiotic prophylaxis (CAP). We assessed the impact of the susceptibility of index UTI to prophylactic antibiotics in breakthrough UTIs in children with primary VUR receiving CAP. Methods We retrospectively reviewed the medical records of 81 children with primary VUR who were diagnosed after febrile or symptomatic UTI and subsequently received trimethoprim-sulfamethoxazole (TMP-SMX) as CAP between January 2010 and December 2013. We allocated children to a susceptible group or a resistant group based on the susceptibility of index UTI to TMP-SMX. We evaluated patient demographics and clinical outcomes after CAP according to the susceptibility of index UTI to TMP-SMX. Multivariate analysis was used to identify the predictive factors for breakthrough UTI. Results Of the 81 children, 42 were classified into the susceptible group and 39 into the resistant group. The proportion of breakthrough UTI was 31.0% (13/42) in the susceptible group and 53.8% (21/39) in the resistant group (P = 0.037). Progression of renal scarring was observed in 0% of children in the susceptible group and 15% in the resistant group (P = 0.053). Multivariate analysis showed that TMP-SMX resistance and initial renal scarring were significant predictors of breakthrough UTI. Conclusion Susceptibility of index UTI to prophylactic antibiotics is a risk factor of breakthrough UTI and is associated with poor clinical outcomes in children with primary VUR receiving CAP.