Different impact of the appropriateness of empirical antibiotics for bacteremia among younger adults and the elderly in the ED

Objectives: To investigate the clinical impact of age on bacteremia among adults visiting the emergency department (ED). Methods: Bacteremic adults visiting the ED from January 2008 to December 2008 were identified retrospectively. Demographic characteristics, severity, bacteremic pathogens with in vitro susceptibility, antimicrobial agents, and outcomes determined from chart records were analyzed as a case-control study. Results: Of 518 eligible bacteremic adults, 288 (55.6%) elderly patients (≥ 65 years old) were case patients and 230 younger patients (< 65 years) were regarded as control patients. The 28-day mortality rate was higher in the case patients than that in the control patients (11.8% vs 6.1%, P =.02). The proportion of inappropriate empirical antibiotic therapy between the survivors and nonsurvivors was similar in control patients (69.4% vs 64.3%, P =.77); but for the case patients, the proportion of inappropriate empirical antibiotic therapy in the survivors was lower than that in the non-survivors (27.6% vs 44.1%, P =.04). Of note, inappropriate empirical antibiotic therapy was also one of independent risk factors of 28-day mortality by the multivariate analyses in the case patients (odds ratio [OR] 3.65; P =.049). Other independent predictors of 28-day mortality in case patients included a high Pittsburgh bacteremia score (≥ 4 points; OR 22.16; P <.001), bacteremia due to foci other than urinary tract infection (OR 9.07; P =.002), malignancy (OR 10.87; P <.001), coronary artery disease (OR 5.68; P =.01), and high serum creatinine (> 1.5 mg/dL; OR 3.44; P =.04). Conclusions: For bacteremic adults, this study demonstrated the impact of inappropriate empirical antibiotic therapy on patients' outcome in the elderly was greater than that in the younger adults.