Antimicrobial strategy for severe community-acquired legionnaires' disease: A multicentre retrospective observational study

Abstract

Background: Legionnaires' disease (LD) is an important cause of community-acquired pneumonia with high mortality rates in the most severe cases. Objectives: To evaluate the effect of antimicrobial strategy on ICU mortality. Methods: Retrospective, observational study including patients admitted to 10 ICUs for severe communityacquired LD over a 10 year period (2005-15) and receiving an active therapy within 48 h of admission. Patients were stratified according to the antibiotic strategy administered: (i) fluoroquinolone-based versus nonfluoroquinolone- based therapy; and (ii) monotherapy versus combination therapy. The primary endpoint was in- ICU mortality. Amultivariable Cox model and propensity score analyses were used. Results: Two hundred and eleven patients with severe LD were included. A fluoroquinolone-based and a combination therapy were administered to 159 (75%) and 123 (58%) patients, respectively. One hundred and fortysix patients (69%) developed acute respiratory distress syndrome and 54 (26%) died in the ICU. In-ICU mortality was lower in the fluoroquinolone-based than in the non-fluoroquinolone-based group (21% versus 39%, P=-0.01), and in the combination therapy than in the monotherapy group (20% versus 34%, P=0.02). In multivariable analysis, a fluoroquinolone-based therapy, but not a combination therapy, was associated with a reduced risk of mortality [HR=0.41, 95% CI 0.19-0.89; P=0.02]. Conclusions: Patients with severe LD receiving a fluoroquinolone-based antimicrobial regimen in the early course of management had a lower in-ICU mortality, which persisted after adjusting for significant covariates.