A case of legionellosis during treatment with a TNFalpha antagonist.

We report a patient with Legionella pneumophila pneumonia after infliximab therapy for rheumatoid arthritis. Arguments are discussed for an emerging incidence of infections with intracellular microorganisms, granulomatous and non-granulomatous, in patients having received anti-TNFalpha therapy. These discussions consist of clinical and epidemiological data, experimental data in animals, theoretical evidence, and we provide a possible pathogenetic mechanism.