Comparison of polymyxin B with other antimicrobials in the treatment of ventilator-associated pneumonia and tracheobronchitis caused by Pseudomonas aeruginosa or Acinetobacter baumannii

Purpose This study was designed to compare the efficacy of polymyxin B with other antimicrobials in the treatment of ventilator-associated pneumonia (VAP) and tracheobronchitis (VAT) by Pseudomonas aeruginosa or Acinetobacter baumannii. Methods A prospective cohort study was performed. Patients >18 years of age with the diagnosis of VAP or VAT who received appropriate therapy for >48 h were analyzed. The primary outcome was 30-day mortality. Clinical covariates were assessed and compared between the groups. Results A total of 67 episodes were analyzed: 45 (67 %) treated with polymyxin B and 22 (33 %) with comparators. The crude 30-day mortality was 53 % (24 of 45) in the polymyxin B group and 27 % (6 of 22) in the comparator group (P = 0.08). Multivariable analysis using Cox regression models indicated that polymyxin B treatment was independently associated with increased mortality. Conclusions Polymyxin B treatment in the currently recommended dosage may be inferior to other drugs in the treatment of VAP and VAT caused by organisms tested as susceptible in vitro to this agent.