Abstract
Legionella pneumophila is a significant cause of community-acquired pneumonia (CAP) and often necessitates hospitalization. Lascufloxacin (LSFX), a novel fluoroquinolone with high pulmonary penetration, has demonstrated efficacy in treating Legionella pneumonia in hospitalized patients. However, its use in an outpatient setting for Legionella pneumonia has not been previously documented, despite its favorable pharmacokinetics and safety profile. We present a 49-year-old man with a history of smoking and dyslipidemia who developed a high fever, headache, and malaise. In addition to the presence of relative bradycardia, chest imaging revealed right lower lobe pneumonia, and a urinary antigen test confirmed Legionella pneumophila infection. Despite this diagnosis, his condition remained stable (A-DROP score: 1), allowing for outpatient management. He was prescribed LSFX 75 mg/day for 10 days, with close monitoring via home pulse oximetry and scheduled frequent follow-up visits. His fever was resolved by day 3, and he fully recovered without complications or adverse effects. This is the first reported case of successful outpatient treatment of Legionella pneumonia with LSFX. The decision for outpatient therapy was based on the patient's stable condition based on A-DROP (age, dehydration, respiratory failure, orientation disturbance, and low blood pressure) scoring, LSFX's excellent bioavailability and pulmonary penetration, and its lack of renal dose adjustment requirements. However, the A-DROP scoring system may underestimate Legionella pneumonia severity, necessitating careful patient selection. LSFX appears to be a safe and effective option for outpatient management of mild Legionella pneumonia. This case highlights its potential as an alternative to inpatient treatment, but further studies are required to confirm its broader applicability.