Imipenem, Meropenem, or Doripenem To Treat Patients with Pseudomonas aeruginosa Ventilator-Associated Pneumonia

Only limited data exist on Pseudomonas aeruginosa ventilator-associated pneumonia (VAP) treated with imipenem, meropenem, or doripenem. Therefore, we conducted a prospective observational study in 169 patients who developed Pseudomonas aeruginosa VAP. Imipenem, meropenem, and doripenem MICs for Pseudomonas aeruginosa isolates were determined using Etests and compared according to the carbapenem received. Among the 169 isolates responsible for the first VAP episode, doripenem MICs were lower (P < 0.0001) than those of imipenem and meropenem (MIC(50)s, 0.25, 2, and 0.38, respectively); 61%, 64%, and 70% were susceptible to imipenem, meropenem, and doripenem, respectively (P was not statistically significant). Factors independently associated with carbapenem resistance were previous carbapenem use (within 15 days) and mechanical ventilation duration before VAP onset. Fifty-six (33%) patients had at least one VAP recurrence, and 56 (33%) died. Factors independently associated with an unfavorable outcome (recurrence or death) were a high day 7 sequential organ failure assessment score and mechanical ventilation dependency on day 7. Physicians freely prescribed a carbapenem to 88 patients: imipenem for 32, meropenem for 24, and doripenem for 32. The remaining 81 patients were treated with various antibiotics. Imipenem-, meropenem-, and doripenem-treated patients had similar VAP recurrence rates (41%, 25%, and 22%, respectively; P = 0.15) and mortality rates (47%, 25%, and 22%, respectively; P = 0.07). Carbapenem resistance emerged similarly among patients treated with any carbapenem. No carbapenem was superior to another for preventing carbapenem resistance emergence.