Legionella pneumophila Serotype 1 Pneumonia in Patient Receiving Adalimumab

Terry C. Wuerz

, Owen Mooney, and Yoav Keynan

Author affiliations: University of Manitoba, Winnipeg, Manitoba, Canada

Abstract

We describe a case of severe pneumonia caused by Legionella pneumophila serotype 1 in a woman receiving the tumor necrosis factor–α antagonist to treat rheumatoid arthritis. As use of tumor necrosis factor–α inhibitors increase, clinicians should consider their possible association with legionellosis.

Legionella pneumophila, a gram-negative rod normally inhabiting aquatic environments, causes severe infections, including pneumonia (legionellosis) that can be acquired in the community or in hospitals. Traditional risk factors for legionellosis include smoking, corticosteroid use, and chronic lung disease (1). Receipt of a tumor necrosis factor–α antagonist (TNF-α antagonists: infliximab, adalimumab, etanercept) generally has not been considered a risk factor for legionellosis.
In the past 2 decades, use of TNF-α antagonists have revolutionized the treatment of rheumatoid arthritis, inflammatory bowel disease, psoriasis, and other inflammatory conditions. After introduction of these agents, a growing body of postmarketing literature has shown an increased risk for disease from Mycobacterium tuberculosis, endemic mycoses, and intracellular bacterial pathogens, including Legionella pneumophila (2). We report a severe case of right upper lobe pneumonia caused by L. pneumophila serotype 1, mimicking M. tuberculosis reactivation, in a patient receiving the TNF-α antagonist adalimumab for rheumatoid arthritis.