Is Polymicrobial Bacteremia an Independent Risk Factor for Mortality in Bacteremia?

This retrospective observational study assessed the differences between monomicrobial and polymicrobial bacteremia and identified possible independent risk factors for 14-day mortality. There were 379 patients with bacteremia admitted to a tertiary care center in northern Taiwan between August 2008 and July 2015 enrolled for data analysis. Among them, 89 patients (23.5%) had polymicrobial bacteremia and 290 patients (76.5%) had monomicrobial bacteremia. No significant difference in 14-day mortality was observed between patients with monomicrobial and polymicrobial bacteremia (26.9% vs. 29.2%, = 0.77). Logistic regression controlled for confounders demonstrated that polymicrobial bacteremia was not an independent predictor of mortality, whereas appropriate antimicrobial therapy was independently associated with reduced mortality. Higher 14-day mortality rates were observed in the polymicrobial bacteremic patients with concomitant isolation of , , and spp. from the bloodstream. Compared with patients with monomicrobial multidrug-resistant (MDRAb) bacteremia, those with MDRAb concomitant with Gram-negative bacilli bacteremia had a worse outcome. Polymicrobial bacteremia was not associated with a higher 14-day mortality rate than that of monomicrobial bacteremia, although more deaths were observed when certain Gram-negative bacteria were concomitantly isolated. Appropriate antimicrobial therapy remains an important life-saving measure for bacteremic patients.