Mortality after Delay of Adequate Empiric Antimicrobial Treatment of Bloodstream Infection

Abstract

Timely empiric antimicrobial therapy is one of the cornerstones of the management of suspected bloodstream infection (BSI). However, studies about the effects of empiric therapy on mortality have reported inconsistent results. The objective of this study was to estimate the effect of delay of appropriate empiric therapy on early mortality in patients with BSI. Methods: Data for the propensity score matching (PSM) study were obtained from a cohort of patients with BSI. Inadequate empiric treatment was defined as in vitro resistance to the antimicrobial regimen administered <6 h after blood cultures were taken. The primary outcome measure was 14-day mortality. Thirty-day mortality and median length of stay (LOS) were secondary outcomes. PSM was applied to control for confounding. Results: Of a total of 893 included patients with BSI, 35.7% received inadequate initial empiric treatment. In the PSM cohort (n = 334), 14-day mortality was 9.6% for inadequate antibiotic treatment, compared to. 10.2% in adequate empiric treatment (p = 0.85). No prolonged median LOS was observed in patients who initially received inadequate therapy (10.5 vs. 10.7 days, p = 0.89). Conclusions: In this study, we found no clear effect of inadequate empirical treatment on mortality in a low-risk BSI population. The importance of early empiric therapy compared to other determinants, may be limited. This may not apply for specific subpopulations, e.g., patients with sepsis.

Keywords: antibiotic stewardship; antimicrobial resistance; blood cultures; bloodstream infection; empiric therapy.

Figure 1

Standardized differences of study variables before- and after propensity score matching. An * indicates that the variable was included in the propensity score model. The shaded area represents the distribution with a standardized difference (SDD) <10. MDRO = Multidrug-resistant pathogen. TTP = time to positivity. ICU = intensive care unit. Fever was defined as temperature > 38.5 °C. Neutropenia: absolute neutrophil count <0.5 × 10⁹/mL.