A Case of Community-Acquired Pneumonia Due to Legionella pneumophila Serogroup 9 Wherein Initial Treatment with Single-Dose Oral Azithromycin Appeared Useful.

Legionella species are important causative pathogens for severe community-acquired pneumonia (CAP). Most cases of Legionella pneumonia are due to Legionella pneumophila serogroup 1, and CAP due to L. pneumophila serogroup 9 is rare. A fourth case of CAP due to L. pneumophila serogroup 9 has been reported, and initial treatment using single-dose oral azithromycin appeared useful. Azithromycin or fluoroquinolone injection is usually recommended for the treatment of Legionella pneumonia, and no previous reports have shown the effectiveness of single-dose oral azithromycin. This case report is therefore valuable from the perspective of possible treatment for mild to moderate Legionella pneumonia using single-dose oral azithromycin.