We prospectively evaluated the efficacy and toxicity of intravenously administered colistin in 35 episodes of ventilator-associated pneumonia (VAP) due to multidrug-resistant Acinetobacter baumannii. Microbiological diagnosis was performed with use of quantitative culture. In 21 patients, the episodes were caused by a strain susceptible exclusively to colistin (the CO group) and were all treated with this antimicrobial intravenously. In 14 patients, the episodes were caused by strains that remained susceptible to imipenem and were treated with imipenem-cilastatin (the IM group). Acute Physiology and Chronic Health Evaluation II scores at the time of admission and Sequential Organ Failure Assessment scores at time of diagnosis were similar in both groups. VAP was considered clinically cured in 57% of cases in both groups. In-hospital mortality rates were 61.9% in the CO group and 64.2% in the IM group, and the VAP-related mortality rates were 38% and 35.7%, respectively. Four patients in the CO group and 6 in the IM group developed renal failure. Neurophysiological evaluation was performed during 12 episodes in the CO group, but it revealed no signs of neuromuscular blockade. Intravenous colistin appears to be a safe and effective alternative to imipenem for the management of VAP due to carbapenem-resistant strains of A. baumannii.

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.

AB acquisition involved an excess LOS in ICU patients and increased risk of death, but the latter could be found only in patients with proven infection.

Nosocomial bacteremia caused by Acinetobacter baumannii (AB) is of increasing concern in critically ill patients, and the risk factors for this infection are not well established. An inception cohort study in a 40-bed medical and surgical intensive care unit (ICU) at a single institution was conducted during a 2-year period to determine the risk factors for AB nosocomial bacteremia. Risk factors related to the underlying diseases, the clinical picture at admission, and those acquired during the stay in the ICU were recorded upon admission and daily throughout the ICU stay. We defined an "invasive procedures index" as the number of invasive procedures performed every day during the ICU stay before the onset of AB bacteremia divided by the number of days in the ICU before the onset of AB bacteremia. Risk factors that were independently associated with AB bacteremia were immunosuppression, unscheduled admission to the hospital, respiratory failure at ICU admission, previous antimicrobial therapy, previous sepsis in the ICU, and the invasive procedures index.