SAN DIEGO, CA—Patients with good prognoses suffer longer hospitalizations when they receive inappropriate empirical antimicrobial therapy for E. coli and other gram-negative bloodstream infections, according to study findings reported at IDWeek 2015.

“Inappropriate empirical antimicrobial therapy is associated with prolonged hospital length of stay in patients with gram-negative bloodstream infection at both ends of the spectrum of illness,” reported lead study author Sara Cain, BS, University of South Carolina School of Medicine, Columbia, South Carolina, and coauthors.

“This demonstrates benefit from appropriate empirical antimicrobial therapy in patients with BSIMRS (Bloodstream Infection Mortality Risk Score) <5 and adds to previously described survival benefits in those with BSIMRS ≥5,” she concluded.

Appropriate empirical antimicrobial therapy for gram-negative bloodstream infection has been shown to improve survival among patients with “guarded” BSIMRS-predicted prognosis (BSIMRS ≥5) but not patients with good (BSIMRS <5) prognosis at initial presentation, for whom empirical therapy’s benefits has been “unclear,” Cain noted.

To help clarify the role of empirical antimicrobial therapy on hospital length of stay among patients good BSIMRS prognosis for gram-negative bloodstream infections, the research team identified 830 patients diagnosed with first episodes of gram-negative bloodstream infection between 2010–2013 at Palmetto Health Hospitals in Columbia, South Carolina. Of these patients, 469 had BSIMRS <5 and 361 patients had BSIMRS ≥5.

E. coli was the most common gram-negative bloodstream infection, she noted, affecting 444 (54%) patients.

“Variables that were independently associated with increased risk of remaining hospitalized following gram-negative BSI included BSIMRS (adjusted hazard ratio [aHR] 1.14 per BSIMRS point; 95% CI: 1.11, 1.17; P<0.001) and inappropriate empirical empirical therapy (aHR 1.41; 95% CI: 1.07, 1.91; P=0.01),” Cain reported. “After stratification based on BSIMRS, median hospital length of stay with appropriate and inappropriate empirical antimicrobial therapy was 7 and 10 days, respectively, in patients with BSIMRS <5 (P=0.03); and 13 and 17 days, respectively, in those with BSIMRS ≥5 (P=0.02).”