Acinetobacter baumannii ventilator-associated pneumonia:: epidemiological and clinical findings

Objective: To investigate prognostic factors and predictors of Acinetobacter baumannii isolation in ventilator-associated pneumonia (VAP). We specifically analyzed these issues for imipenem-resistant episodes. Design and setting: All episodes of VAP are prospectively included in a database. Information about risk factors was retrieved retrospectively. Patients: Eighty-one patients exhibiting microbiologically documented VAP: 41 by A. baumannii (26 by imipenem-resistant) and 40 by other pathogens. Measurements and results: The following variables were noted: underlying diseases, severity of illness, duration of mechanical ventilation and of hospitalization before VAP, prior episode of sepsis, previous antibiotic, corticosteroid use, type of nutrition, renal replacement therapy, reintubation, transportation out of the ICU, micro-organisms involved in VAP, concomitant bacteremia, clinical presentation, Sequential Organ Failure Assessment (SOFA) scale on the day of diagnosis, and adequacy of empirical antibiotic therapy. Prior antibiotic use was found to be associated with development of VAP by A. baumannii (OR 14). Prior imipenem exposure was associated with the isolation of imipenem-resistant strains (OR 4). SOFA score on the day of diagnosis was the only predictor of in-hospital mortality (OR 1.22); adequacy of empirical antibiotic therapy was a protective factor (OR 0.067). Conclusions: Our results confirm that prior exposure to antimicrobials is an independent predictor for the development of A. baumannii VAP, the prognosis of which is similar to that of infections caused by other pathogens. This study highlights the importance of initial antibiotic choice in VAP or whatever cause.