Impact of Inadequate Empiric Antimicrobial Therapy on Clinical Outcomes of Patients With Escherichia coli or Klebsiella Species Bacteremia

This study was conducted to evaluate the effect of inadequate empiric antimicrobial therapy (IEAT) on mortality of patients with Escherichia coli or Klebsiella species bacteremia. Patients with E coli or Klebsiella species bacteremia were retrospectively analyzed to determine the effect of IEAT on 14-day mortality. IEAT of bacteremia was defined as administration of an antimicrobial agent to which the microorganism responsible for the bacteremia was resistant. IEAT was significantly associated with central venous catheter placement, Klebsiella species, and antimicrobial resistance among the 135 patients with E coli or Klebsiella species bacteremia (110 adequate, 25 inadequate). IEAT significantly increased 14-day mortality (32% vs 19%; P = .019). The increased 14-day mortality associated with IEAT was consistent among patients infected with E coli (33% vs 11%) or Klebsiella species (31% vs 15%). Independent risk factors for 14-day mortality in the multivariate analysis included Acute Physiology and Chronic Health Evaluation II (APACHE II) score (odds ratio [OR] 1.16; 95% confidence interval [CI] = 1.07-1.27), IEAT (OR 9.4; 95% CI = 1.36-65.14), and initial imipenem therapy (OR 20.66; 95% CI = 1.48-287.74). Of the 6 patients receiving empiric imipenem/cilastatin, 3 had APACHE II scores ≥ 30 (all 3 of these patients died). The 14-day mortality rate was similar for patients who received IEAT, regardless of whether their therapy was changed (32%) or not (33%). Based on these results and previous studies, greater efforts should be made to identify patients at risk for resistant pathogens before initiating antimicrobial therapy.