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 antim icrobial treatment for bloodstream infections and clinical outcomes among p atients requiring ICU admission. Design: Prospective cohort study. Setting: A medical ICU (19 beds) and a surgical ICU (18 beds) from a univer sity-affiliated urban teaching hospital. Patients: Between July 1997 and July 1999, 492 patients were prospectively evaluated. Intervention: Prospective patient surveillance and data collecti on. Results: One hundred forty-seven patients (29.9%) received inadequate antim icrobial treatment for their bloodstream infections. The hospital mortality rate of patients with a bloodstream infection receiving inadequate antimic robial treatment (61.9%) was statistically greater than the hospital mortal ity rate of patients with a bloodstream infection who received adequate ant imicrobial treatment (28.4%; relative risk, 2.18; 95% confidence interval [ CI], 1.77 to 2.69; p < 0.001). Multiple logistic regression analysis identi fied the administration of inadequate antimicrobial treatment as an indepen dent 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 pa thogens and their associated rates of inadequate antimicrobial treatment in cluded vancomycin-resistant enterococci (n = 17; 100%), Candida species (n = 41; 95.1%), oxacillin-resistant Staphylococcus aureus (n = 46; 32.6%), co agulase-negative staphylococci (n = 96; 21.9%), and Pseudomonas aeruginosa (n = 22; 10.0%). A statistically significant relationship, was found betwee n the rates of inadequate antimicrobial treatment for individual microorgan isms and their associated rates of hospital mortality (Spearman correlation coefficient = 0.8287; p = 0.006), Multiple logistic regression analysis al so 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 2.7 4; 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 cathet er 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 antimi crobial treatment. Conclusions: The administration of inadequate antimicrobial treatment to cr itically ill patients with bloodstream infections is associated with a grea ter hospital mortality compared with adequate antimicrobial treatment of bl oodstream infections. These data suggest that clinical efforts should be ai med at reducing the administration of inadequate antimicrobial treatment to hospitalized patients with bloodstream infections, especially individuals infected with antibiotic-resistant bacteria and Candida species.