Polymicrobial bloodstream infections per se do not increase mortality compared to monomicrobial bloodstream infections in sepsis patients: a Korean nationwide sepsis cohort study

There is limited information about the outcomes of polymicrobial bloodstream infections in patients with sepsis. We aimed to investigate outcomes of polymicrobial bloodstream infections compared to monomicrobial bloodstream infections. This study used data from the Korean Sepsis Alliance Registry, a nationwide database of prospective observational sepsis cohort. Adult sepsis patients with bloodstream infections from September 2019 to December 2021 at 20 tertiary or university-affiliated hospitals in South Korea were analyzed. Among the 3,823 patients with bloodstream infections, 429 of them (11.2%) had polymicrobial bloodstream infections. The crude hospital mortality of patients with sepsis with polymicrobial bloodstream infection and monomicrobial bloodstream infection was 35.7% and 30.1%, respectively (p = 0.021). However, polymicrobial bloodstream infections were not associated with hospital mortality in the proportional hazard analysis (HR 1.15 [0.97-1.36], p = 0.11). The inappropriate use of antibiotics was associated with increased mortality (HR 1.37 [1.19-1.57], p