Legionellosis: Global Epidemiology and Current Perspectives on Diagnosis and Treatment

Jianwen Ma,1,* Tingyan Dong,2,* Fei Li,3 Chunmei He,4 Biyun Li,4 Zhenyu Liu5 1Department of Respiratory and Critical Care Medicine, Linxia Hui Autonomous Prefecture People’s Hospital, Linxia, Gansu, People’s Republic of China; 2Guangzhou College of Commerce Research Center for Healthy Aging and Social Economic Development, Guangzhou, Guangdong, People’s Republic of China; 3Department of Pharmacy, The Second People’s Hospital of Futian District, Shenzhen, Guangdong, People’s Republic of China; 4Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, People’s Republic of China; 5Department of Pharmacy, Shenzhen Nanshan People’s Hospital, Shenzhen, Guangdong, People’s Republic of China*These authors contributed equally to this workCorrespondence: Zhenyu Liu, Department of Pharmacy, Shenzhen Nanshan People’s Hospital, Shenzhen, Guangdong, People’s Republic of China, Email [email protected] Biyun Li, Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, People’s Republic of China, Email [email protected]: The genus Legionella, first identified in 1977, comprises environmental Gram-negative intracellular bacteria that cause Legionellosis. Ubiquitous in freshwater and artificial water systems, Legionella species have an unclear global incidence, with reported cases likely significantly underestimated. Travel-associated Legionnaires’ disease (TALD) has increased recently and become a surveillance priority. For diagnosis, culture remains the gold standard but is time-consuming. Urinary antigen testing enables rapid screening, yet is mainly restricted to L. pneumophila serogroup 1. Molecular diagnostics, particularly PCR, offer high sensitivity and detect multiple serogroups, facilitating early diagnosis. Therapeutically, macrolides and fluoroquinolones constitute the mainstay of treatment, though evidence supporting combination therapy remains limited. Increasing reports of antimicrobial resistance underscore the need for strengthened antibiotic stewardship and global surveillance. Future efforts should prioritize large-scale epidemiological studies, diagnostic standardization, treatment optimization, and resistance monitoring to reduce disease burden.Keywords: Legionella, Legionellosis, epidemiology, resistance, treatment