Gram-negative bacteraemia in non-ICU patients: factors associated with inadequate antibiotic therapy and impact on outcomes

BACKGROUND: A considerable number of gram-negative bacteraemias occur outside intensive care units (ICUs). Inadequate antibiotic therapy in ICUs has been associated with adverse outcomes; however, there are no prospective studies in non-ICU patients. METHODS: A 6 month (1 August 2006-31 January 2007), prospective cohort study of non-ICU patients with gram-negative bacteraemia in a tertiary-care hospital was performed. Inadequate empirical antibiotic therapy was defined as no antibiotic or starting a non-susceptible antibiotic within 24 h after the initial positive blood culture. RESULTS: Two hundred and fifty non-ICU patients had gram-negative bacteraemia. The mean age was 56.4 (+/-16.1) years. The predominant bacteria in monomicrobial infections were Escherichia coli (24%), Klebsiella pneumoniae (18%) and Pseudomonas aeruginosa (8%). Sixty-one (24%) patients had polymicrobial bacteraemia. Seventy patients (28%) required ICU transfer and 35 (14%) died. Seventy-nine (31.6%) received inadequate empirical antibiotic therapy. These patients were more likely to have a hospital-acquired infection odds ratio (OR) = 1.99, 95% confidence interval (CI) = 1.11-3.56, P = 0.02 and less likely to have E. coli monomicrobial bacteraemia OR 0.40 (95% CI 0.19-0.86), P = 0.02. There were no differences in occurrence of sepsis 72 (91.1%) patients with inadequate versus 159 (93.0%) with adequate therapy; P = 0.6, ICU transfer 20 (25.3%) versus 50 (29.2%); P = 0.5, post-bacteraemia length of stay (median = 6.8 versus 6.1 days; P = 0.09) or death 11 (13.9%) versus 24 (14.0%); P = 1.0. CONCLUSIONS: Nearly one-third of the non-ICU patients with gram-negative bacteraemia received inadequate empirical antibiotic therapy. There was no difference in adverse outcomes between patients receiving inadequate or adequate therapy in this study.