Community-acquired Legionella Pneumonia in the intensive care unit: Impact on survival of combined antibiotic therapy

Objectives: To compare intensive care unit (ICU) mortality in patients with severe community-acquired pneumonia (SCAP) caused by Legionella pneumophila receiving combined therapy or monotherapy. Methods: A prospective multicenter study was made, including all patients with sporadic, community-acquired Legionnaires' disease (LD) admitted to the ICU. Admission data and information on the course of the disease were recorded. Antibiotic prescriptions were left to the discretion of the attending physician and were not standardized. Results: Twenty-five cases of SCAP due to L. pneumophila were included, and 7 patients (28%) out of 25 died after a median of 7 days of mechanical ventilation. Fifteen patients (60%) presented shock. Levofloxacin and clarithromycin were the antibiotics most commonly used in monotherapy, while the most frequent combination was rifampicin plus clarithromycin. Patients subjected to combination therapy presented a lower mortality rate versus patients subjected to monotherapy (odds ratio for death [OR] 0.15; 95%CI 0.02-1.04; p=. 0.08). In patients with shock, this association was stronger and proved statistically significant (OR for death 0.06; 95%CI 0.004-0.86; p=. 0.04). Conclusions: Combined antibiotic therapy decreases mortality in patients with SCAP and shock caused by L. pneumophila.