Analysis of the effectiveness of combination antimicrobial therapy for Legionnaires' disease: A nationwide inpatient...

The effectiveness of monotherapy and combination therapy with quinolones and macrolides for treating Legionnaires' disease remains uncertain; this study aimed to assess the comparative effectiveness of three treatment approaches.

Using a nationwide inpatient database, we analyzed 3560 eligible patients hospitalized for Legionnaires' disease between April 1, 2014, and March 31, 2021; patients were divided into combination therapy, quinolone monotherapy, and macrolide monotherapy groups according to the antibiotics administered within 2 days of admission. We compared in-hospital mortality, total hospitalization costs, and length of stay across these groups using multiple propensity score analysis with inverse probability of treatment weighting.

Of the 3560 patients, there were 564 (15.8%), 2221 (62.4%), and 775 (21.8%) patients in the combination therapy, quinolone monotherapy, and macrolide monotherapy groups, respectively. No significant differences were observed in in-hospital mortality between combination therapy and quinolone monotherapy groups, and between combination therapy and macrolide monotherapy groups. There were no significant differences in total hospitalization costs or length of stay among the three groups.

The study suggests that there may not be a significant advantage in using a combination of quinolones and macrolides over monotherapy for the treatment of Legionnaires' disease. Given the potential for increased side effects, careful consideration is advised when choosing this combination therapy.