Successful Outpatient Treatment of Legionella pneumophila Pneumonia With Lascufloxacin: A Case Report

<i>Legionella pneumophila</i> 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 <i>Legionella</i> pneumonia in hospitalized patients. However, its use in an outpatient setting for <i>Legionella</i> 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 <i>Legionella pneumophila</i> 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 <i>Legionella</i> 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 <i>Legionella</i> pneumonia severity, necessitating careful patient selection. LSFX appears to be a safe and effective option for outpatient management of mild <i>Legionella</i> pneumonia. This case highlights its potential as an alternative to inpatient treatment, but further studies are required to confirm its broader applicability.