Follow-up blood cultures add little value in the management of bacteremic urinary tract infections

Abstract

The need for mandatory confirmation of negative conversion in bacteremic urinary tract infection (UTI) has not been adequately addressed, even though follow-up blood cultures (FUBCs) are still prescribed liberally. The purpose of this study was to identify possible risk factors associated with positive FUBCs. We retrospectively collected data on adult cases of bacteremic UTI with at least one FUBC. Patients were divided into the negative FUBCs and the positive FUBC group, and data of both groups were compared. Of 306 cases of bacteremic UTI, 251 had a negative result from an FUBC and 55 had a positive result. Diabetes mellitus, malignancy, complicated UTI, and initial intensive care unit (ICU) admission were significantly more common in the positive FUBC group than in the negative group (all-P<0.05). Time to defervescence was significantly longer in the positive FUBC group than in the negative group (52.2h vs. 25.3h, P<0.05). A multivariate analysis showed that malignancy, initial ICU admission, CRP>16 (mg/dL), and a time to defervescence of more than 48h were significant factors associated with a positive FUBC. No subsequent cases of bacteremia developed in patients without risk factors associated with a positive FUBC. In bacteremic UTIs, patients with positive FUBCs usually present with higher initial inflammatory markers, longer time to defervescence, more frequent ICU admission rates, and an elevated chance of having cancer. More careful clinical assessment before drawing FUBCs would reduce costs and inconvenience to patients.