The influence of inadequate antimicrobial treatment of bloodstream infections on patient outcomes in the ICU setting

Study objective: To evaluate the relationship between the adequacy of antimicrobial treatment for bloodstream infections and clinical outcomes among patients requiring ICU admission. Design: Prospective cohort study. Setting: A medical ICU (19 beds) and a surgical ICU (18 beds) from a university-affiliated urban teaching hospital. Patients: Between July 1997 and July 1999, 492 patients were prospectively evaluated. Intervention: Prospective patient surveillance and data collection. Results: One hundred forty-seven patients (29.9%) received inadequate antimicrobial treatment for their bloodstream infections. The hospital mortality rate of patients with a bloodstream infection receiving inadequate antimicrobial treatment (61.9%) was statistically greater than the hospital mortality rate of patients with a bloodstream infection who received adequate antimicrobial treatment (28.4%; relative risk, 2.18; 95% confidence interval [CI], 1.77 to 2.69; p < 0.001). Multiple logistic regression analysis identified the administration of inadequate antimicrobial treatment as an independent determinant of hospital mortality (adjusted odds ratio [AOR], 6.86; 95% CI, 5.09 to 9.24; p < 0.001). The most commonly identified bloodstream pathogens and their associated rates of inadequate antimicrobial treatment included vancomycin-resistant enterococci (n = 17; 100%), Candida species (n = 41; 95.1%), oxacillin-resistant Staphylococcus aureus (n = 46; 32.6%), coagulase-negative staphylococci (n = 96; 21.9%), and Pseudomonas aeruginosa (n = 22; 10.0%). A statistically significant relationship, was found between the rates of inadequate antimicrobial treatment for individual microorganisms and their associated rates of hospital mortality (Spearman correlation coefficient = 0.8287; p = 0.006), Multiple logistic regression analysis also demonstrated that a bloodstream infection attributed to Candida species (AOR, 51.86; 95% CI, 24.57 to 109.49; p < 0.001), prior administration. of antibiotics during the same hospitalization (AOR, 2.08; 95% CI, 1.58 to 2.74; p = 0.008), decreasing serum albumin concentrations (1-g/dL decrements) (AOR, 1.37; 95% CI, 1.21 to 1.56; p = 0.014), and increasing central catheter duration (I-day increments) (AOR, 1.03; 95% CI, 1.02 to 1.04; p = 0.008) were independently associated with the administration of inadequate antimicrobial treatment. Conclusions: The administration of inadequate antimicrobial treatment to critically ill patients with bloodstream infections is associated with a greater hospital mortality compared with adequate antimicrobial treatment of bloodstream infections. These data suggest that clinical efforts should be aimed at reducing the administration of inadequate antimicrobial treatment to hospitalized patients with bloodstream infections, especially individuals infected with antibiotic-resistant bacteria and Candida species.