Duration of antibiotic therapy for ventilator-associated pneumonia caused by non-fermentative gram-negative bacilli

Chastre et al. compared eight and 15 days of antibiotic therapy for ventilator-associated pneumonia (VAP), finding no difference in outcome with the exception of VAP caused by non-fermentative gram-negative bacilli (NFGNB), for which a higher recurrence rate was seen in the shorter-duration group (JAMA 2003;290:2588-2598). We recently examined our institutional experience with VAP caused by NFGNB to determine whether shorter courses of antibiotic therapy were associated with higher rates of recurrence.

Data collected on all patients completing treatment for VAP in a surgical/trauma intensive care unit from December 1996 to October 2004 were analyzed retrospectively for the relations between the duration of antibiotic therapy and recurrence and in-hospital mortality rates.

Of the 452 episodes of VAP, 154 were associated with NFGNB. Twenty-seven patients were treated with 3-8 days (mean 6.4 +/- 0.3 days) of antibiotics, whereas 127 received nine or more days (mean 17.1 +/- 0.7 days) of therapy. The recurrence rate for infections treated with the shorter course was 22% vs. 34% for patients receiving nine or more days of antibiotics (p = 0.27). The mortality rates were 22% and 14%, respectively (p = 0.38). Similar trends were demonstrated for infections caused by other organisms.

We did not find a higher recurrence rate in patients with VAP caused by NFGNB who received shorter courses of antibiotic therapy. On the contrary, those patients receiving shorter courses trended toward lower rates of recurrence. Pending further prospective trials addressing the duration of antibiotic treatment for patients with VAP caused by NFGNB, shorter courses of treatment, perhaps based on improvement in clinical parameters, may be warranted.