Inadequate antibiotic treatment of microbiologically proven infection is an independent determinant of hospital mortality for patients requiring intensive care

Purpose: The adequacy of antimicrobial therapy for patients with infection has been evaluated in small clinical investigations and for specific infections (e.g., bacteremia, nosocomial pneumonia). At our institution, the historical practice has been to use broad-spectrum cephalosporin antibiotics for the treatment of suspected gram-negative bacterial infections. We set out to examine the importance of this medical treatment in a large intensive care unit (ICU) patient population. Methods: The first 1000 patients in a 1-year ongoing investigation are reported. Results: Overall we found that 29.5% of our ICU patients had an infection (8.8% nosocomial infection, 16.9% community-acquired and 3.7% both community-acquired and nosocomial infections). There were 92 patients who received inadequate antibiotic therapy for a microbiologically proven infection. The mortality rate of these patients was statistically greater than the mortality rate of patients with an infection which was adequately treated with the selected antibiotic regimen (53.3% versus 19.2%; P<0.001). Multiple logistic regression analysis identified the presence of inadequate antibiotic treatment as being independently associated with hospital mortality (adjusted odds ratio=6.06;95% confidence interval=4.24 to 8.67; P<0.001). The most common cause of inadequate antibiotic therapy was the presence of gram-negative bacterial infection resistant to the prescribed antibiotic regimen (50 of 92 [54.3%] patients receiving inadequate antibiotic treatment). Among these patients, the most common antibiotic class accounting for inadequate treatment were the broad-spectrum cephalosporins (90.0%) Conclusions: Inadequate initial antibiotic treatment of microbiologically documented infections occurring within the ICU setting appears to be relatively common. Clinical Implications: Future studies are needed to confirm these results and to develop interventions aimed at avoiding the administration of inadequate initial antibiotic treatment.