Short course antibiotic therapy for Gram-negative hospital-acquired pneumonia in the critically ill.

Hospital-acquired pneumonia (HAP) is a common cause of morbidity and mortality in the critically ill, yet the optimal duration of antibiotic therapy is unknown. Too short a course may lead to treatment failure, whereas too long a course may lead to increased antibiotic resistance, antibiotic-related morbidity and increased costs. Standard duration of antibiotic therapy for Gram-negative (GN-)HAP at our institution is 5 days, significantly shorter than advocated in many current guidelines. We performed a retrospective review of all cases of GN-HAP on our critical care unit fulfilling clinical and microbiological criteria to investigate recurrence rate and mortality following short course antibiotic therapy. Seventy-nine eligible patients with GN-HAP were identified. Of these, 79% were receiving mechanical respiratory support at diagnosis; 42% had GN-HAP due to non-fermenting Gram-negative bacilli (NF-GNB) and 72% were treated with the recommended 5 day course of antibiotics. Two patients had clear evidence of non-resolution of pneumonia after 5 days of therapy. Overall recurrence rate was 14%, with relapse rates significantly higher among patients with NF-GNB when compared to patients with other Gram-negative organisms (17% vs 2%; P=0.03). The overall recurrence rate was no higher than rates reported in earlier studies (17-41%). Critical care mortality (34.2%) was also not in excess of previously reported values (18-57%). In this limited study, use of a 5 day course of appropriate antibiotics for GN-HAP does not appear to increase risk of recurrence or mortality when pneumonia resolution has been achieved prior to the cessation of therapy. Copyright (c) 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.