Impact of urinary tract infection-causative microorganisms on the progression to bloodstream infection: A propensity score-matched analysis

Objectives: We aimed to determine the risk factors for the progression of urinary tract infection (UTI) to bloodstream infection (BSI) and to evaluate the mortality-associated factors in patients with urinary tract-related BSI (UT-BSI). Methods: A propensity score-matched study was conducted using clinical data from all adult patients with UTIs in two South Korean hospitals. Results: A total of 84,406 patients with UTIs were enrolled. The relative incidence of UTIs caused by Escherichia coli decreased along with an increase in the incidence of Candida species infections during the study period. UTI caused by E. coli, Klebsiella pneumoniae, Staphylococcus aureus, and Candida species had a relatively high rate of progression to BSI. UT-BSI caused by Candida species (adjusted odd ratio 5.67; 95% confidence interval 3.97–8.11; p < 0.001) was significantly associated with high 30-day mortality. Conclusions: UTI-causative microorganisms were associated with both progression to UT-BSI and 30-day mortality in patients with UT-BSI. Considering the trend of increasing age of patients and more frequent use of indwelling urologic devices, UT-BSIs caused by other microorganisms than E. coli could be a more serious medical burden in the future.