First reported United States case of Legionella pneumophila serogroup 1 pneumonia in a patient receiving anti-tumor necrosis factor-alpha therapy.

Legionellosis has been reported to be an extremely rare disease in Hawai'i. The authors report a case of a 67-year-old woman with a history of rheumatoid arthritis treated with long-term adalimumab who developed severe right-sided community-acquired pneumonia and a parapneumonic effusion. Legionella pneumophila serogroup 1 was confirmed as the microbiologic cause based on a positive urine Legionella antigen as well as direct fluorescent antibody and Legionella culture of bronchoalveolar lavage. This is the first reported case of Legionella pneumonia associated with anti-tumor necrosis factor (TNF)-alpha therapy in the United States. There have been several reports of an increased association between legionellosis and treatment with a TNF-alpha antagonist. With the increasing use of TNF-alpha antagonists, Legionella pneumophila should be recognized as a potential re-emerging pathogen. Clinicians should particularly consider the diagnosis of legionellosis in patients who are immunocompromised, including those who receive anti-TNF-alpha therapy, or who have severe pneumonia. In such cases, there should be a low threshold for including empiric Legionella antimicrobial coverage until the diagnosis can be confirmed or reasonably excluded.