Acute respiratory distress syndrome in patients with Legionella pneumonia

Objective. The relationship between specific causative organisms and development of ARDS in pneumonia patients has not been explored. Several case reports have described the development of ARDS in patients with Legionella pneumonia. The aim is of this study was to determine frequency and outcomes of ARDS in patients with Legionella Pneumonia. Methods. A retrospective cohort study of patients with Legionella pneumonia hospitalized at two Mayo Clinic Rochester hospitals was conducted. To identify the patients with Legionella pneumonia we searched the Mayo Clinic Life Sciences System (MCLSS) database from 01/01/2003 to 12/31/2007. Electronic medical records of patients with active Legionella pneumonia based on positive cultures and/or urinary antigen were reviewed. ARDS was diagnosed on the basis of the criteria of the North American/European consensus conference definition. Results. We identified 15 patients with microbiologically proven Legionella pneumonia of whom 11 were admitted to the intensive care unit (ICU), 6 required mechanical ventilation and 5 met the criteria for ARDS. Age (median 42 vs. 50 years, p=0.32) and gender (4/10 vs. 1/5 female, p=0.60) were similar in patients with and without ARDS. Septic shock was present in 4 of the 5 patients with ARDS and only 1 without. Patients with ARDS had longer ICU length of stay (median 9 vs. 1 days, P=0.03). Only one patient (from the ARDS group) died in the hospital. Conclusion. In this retrospective study ARDS occurred in one third of patients with microbiologically proven Legionella pneumonia and was associated with prolonged length of ICU stay.