Consequences of treated versus untreated asymptomatic bacteriuria in the first year following kidney transplantation: retrospective observational study.

Asymptomatic bacteriuria (AB) is frequent among kidney transplant patients during the first year post transplantation. Currently, there are no clear guidelines for the antibiotic treatment of AB among these patients. We examined the outcomes of treatment versus no treatment of AB in kidney transplant patients during the first year post transplantation. A retrospective cohort study including adults >16 years of age transplanted in one center between 1/2004 and 12/2010 was undertaken. The primary outcome was a composite of hospitalization for symptomatic urinary tract infection (UTI) or more than 25 % reduction in the estimated glomerular filtration rate (eGFR) 30 days after the documentation of AB. Secondary outcomes included symptomatic UTIs following the episode of AB, persistent recurrent AB, total days in hospital, mortality, adverse events, and resistance development. A total of 112 patients with AB fulfilled the inclusion criteria. Twenty-two patients received antibiotic treatment (19.6 %), while 90 patients did not. The primary outcome occurred in 4/22 (18.2 %) of the treated patients versus 5/90 (5.6 %) of the untreated patients [odds ratio (OR) = 3.78, 95 % confidence interval (CI) 0.9-15]. The risk of developing symptomatic UTI after AB was almost three times higher (p < 0.05) and the total number of hospitalization days at 6 months post AB was also significantly higher (p < 0.026) in the treated group. No patient died during the study period. UTI caused by bacteria resistant to the antibiotic used for the treatment of AB occurred in 36 % of the treated patients. We observed no benefit for the antibiotic treatment of AB in the short- and long-term follow-up. A prospective observational study is needed.