Recurrence of Gram-negative nosocomial pneumonia in the critically ill patient following short-course antibiotic therapy

Background

The optimal duration of antibiotic therapy for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) is not clear. A multicentre randomised controlled trial indicated similar clinical efficacy for 8 versus 15 days of antibiotic therapy for VAP, with less emergence of multiresistant organisms following the shorter course [1]. Pseudomonas aeruginosa is difficult to eradicate, however, and American Thoracic Society guidelines for treatment of HAP due to P. aeruginosa recommend 14 days of therapy [2]. Our aim was to study the rate of recurrence following treatment of Gram-negative HAP in a critically ill population with short-course (typically 5 days) antibiotic therapy.

Materials and methods

We retrospectively reviewed 50 patients treated consecutively with short-course (typically 5 days) antibiotic therapy for Gram-negative HAP in a UK teaching hospital critical care unit from 2004 to 2007. Pneumonia was defined as semi-quantitative respiratory culture (≥2+) of a single Gram-negative isolate, clinical pulmonary infection score ≥6 and initiation of antibiotic therapy. Recurrence of HAP was defined either as relapse (pure growth of the organism causing the initial infection) or reinfection (due to a different organism). Patients were studied until hospital discharge or death.

Results

Demographic and outcome data are summarised in Table 1. The commonest causative organisms were P. aeruginosa (42%), Enterobacter species (14%) and Klebsiella species (14%). Two patients died before completing the initial course of antibiotics.

Table 1 Demographic and outcome data

Conclusion

Treatment of Gram-negative HAP in the critically ill patient with short-course antibiotic therapy is associated with a low rate of recurrence (10.4%). This compares favourably with reported recurrence rates of 18–26% following ≥2 weeks of antibiotic therapy for VAP [1, 3, 4].