Appropriate Antimicrobial Therapy for Bloodstream Infections Lowers Mortality Risk

Patients hospitalized with bloodstream infections (BSIs) who received appropriate initial empirical antimicrobial therapy were found to have a lower in-hospital mortality risk. These study results were published in JAMA Network Open.

In this retrospective cross-sectional study, researchers analyzed data captured between 2016 and 2020 from patients hospitalized with BSIs. The analysis comprised 183 hospitals in the United States, representing 32,100 patients. The endpoint was in-hospital mortality during the index hospitalization. Patients were divided into 3 groups, including those infected with either gram-negative rods (GNRs), gram-positive cocci (GPC), or Candida species. Patients within these groups were further divided into those who did vs did not receive appropriate initial antimicrobial therapy. Appropriate therapy was defined as receipt of at least 1 new antimicrobial agent to which the isolated pathogen was susceptible within 2 days of blood sample collection. Multilevel logistic regression models were used to estimate the association between appropriate initial antimicrobial therapy and in-hospital mortality.

Among patients included in the analysis, 46.6% were positive for GNRs, 52.5% were positive for GPC, and 0.9% were positive for Candida species. Of these patients, 94.4%, 97.0%, and 65.1% received appropriate initial antimicrobial therapy, respectively.

Overall, the mean (SD) patient age was 64 (16) years, 54.8% were men, 69.9% were non-Hispanic White, and the rate of in-hospital mortality was 14.3%. The most commonly isolated pathogens included Escherichia coli (58.4%) and Staphyloccocus aureus (31.8%), and most patients had pulmonary- or genitourinary-related infections. Of patients infected with S aureus, methicillin-resistant S aureus (MRSA) was isolated from 43.6%.

Compared with inappropriate antimicrobial therapy, receipt of appropriate therapy was associated with decreased in-hospital mortality risk among patients infected with GNRs (adjusted odds ratio [aOR], 0.52; 95% CI, 0.42-0.64), GPC (aOR, 0.60; 95% CI, 0.47-0.78), and Candida species (aOR, 0.43; 95% CI, 0.21-0.87). Similar results were observed after adjustments for markers of disease severity.

The researchers performed a sensitivity analysis after stratifying patients who did vs did not receive appropriate initial antimicrobial therapy by specific pathogens. Among patients who received appropriate therapy, in-hospital mortality risk was decreased for those infected with E coli (aOR, 0.54; 95% CI, 0.31-0.93), Klebsiella species (aOR, 0.54; 95% CI, 0.31-0.93), S aureus (aOR, 0.40; 95% CI, 0.27-0.61), MRSA (aOR, 0.46; 95% CI, 0.30-0.71), and Enterococcus species (aOR, 0.48; 95% CI, 0.30-0.77).

Limitations include the retrospective study design, the inability to obtain illness severity scores, and the lack of information on both time to adequate source control and antimicrobial administration.

“Given these findings, it is important for clinicians to carefully choose empirical antimicrobial agents to improve outcomes in patients with BSIs,” the researchers concluded.