Outcome in bacteremia associated with nosocomial pneumonia and the impact of pathogen prediction by tracheal surveillance cultures

Objective: To assess whether pathogen prediction in bacteremia associated with nosocomial pneumonia (NP) by tracheal surveillance cultures improves adequacy of early antibiotic therapy and impacts mortality. Design and setting: A retrospective observational study of a prospectively gathered cohort. This cohort included all adult patients admitted to the ICU of a tertiary care hospital from 1992 through 2001 and who developed bacteremia associated with NP. Measurements and main results: 128 episodes of bacteremia associated with NP were identified. In 110 episodes a tracheal surveillance culture 48-96 h prior to bacteremia was available: this culture predicted the pathogen in 67 episodes (61%). Overall rates of appropriate empiric antibiotic therapy within 24 and 48 h were 62 and 87%, respectively. Pathogen prediction was associated with a significantly higher rate of appropriate antibiotic therapy within 24 h (71 vs 45%; p = 0.01), but not within 48 h (91 vs 82%; p = 0.15). Crude in-hospital mortality was 50%. Pathogen prediction was associated with increased survival in univariate (OR 0.43; CI 0.19-0.93; p = 0.04) and multivariate analysis (OR 0.32; CI 0.12-0.82; p = 0.02). Multivariate analysis further identified age (OR 1.04; CI 1.01-1.07; p = 0.02), increasing APACHE II score (OR 1.08; CI 1.02-1.15; p = 0.01), and methicillin-resistant Staphylococcus aureus (OR 5.90; CI 1.36-25.36; p = 0.01) and Pseudomonas aeruginosa (OR 3.30; CI 1.04-10.4; p = 0.04) as independent risk factors for mortality. Conclusion: Pathogen prediction in bacteremia associated with NP by tracheal surveillance cultures is associated with a higher rate of adequate empiric antibiotic therapy within 24 h and with increased survival.