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

Legionnaires' disease (LD) is an important cause of community-acquired pneumonia with high mortality rates in the most severe cases. To evaluate the effect of antimicrobial strategy on ICU mortality. Retrospective, observational study including patients admitted to 10 ICUs for severe community-acquired 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 non-fluoroquinolone-based therapy; and (ii) monotherapy versus combination therapy. The primary endpoint was in-ICU mortality. A multivariable Cox model and propensity score analyses were used. 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 forty-six 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]. 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.