摘要Since Legionella pneumophila (L. pneumophila) was identified in 1976 as the causative microorganism for severe pneumonia termed Legionnaires Disease (LD), more than 65 species belonging to the genus Legionella have been isolated worldwide[1]. Approximately 20 Legionella spp. have been documented to be pathogenic in humans, primarily leading to transient flu-like illness (Pontiac fever) or rapid and potentially fatal pneumonia (LD). As the most common cause of legionellosis, L. pneumophila is responsible for nearly 95％ of global LD cases, while other non-L. pneumophila species, such as L. longbeachae, L. bozemanii, and L. micdadei, are sporadically isolated from patients, but the isolation rates vary by geography and the patient population[1-3]. In particular, L. micdadei, or Tatlockia micdadei, which was discovered by Hugh Tatlock in 1943, and was also known as the Pittsburgh pneumonia agent in the 1980s, has been recorded in a limited number of respiratory tract infections and rare cases of extra-pulmonary infections, such as secretory diarrhea, endocarditis, brain abscess, and prosthetic joint infection[3].