Background: Patients treated with tumor necrosis factor-alpha (TNF-alpha) antagonists have an increased risk of infection, but infection due to Legionella pneumophila has rarely been described in patients receiving such therapy.
Methods: A registry involving 486 clinical departments in France was designed by a multidisciplinary group (Recherche Axée sur la Tolérance des Biothérapies [RATIO]) to collect data on opportunistic and severe infections occurring in patients treated with TNF-alpha antagonists. All cases are reported to RATIO in accordance with national health authorities and validated by infectious disease experts. The legionellosis rate among patients treated with TNF-alpha antagonists was compared with the rate in France overall.
Results: We report a 1-year consecutive series of 10 cases of L. pneumophila pneumonia in France in 2004, including 6 cases treated with adalimumab, 2 treated with etanercept, and 2 treated with infliximab. The median patient age was 51 years (range, 40-69 years). Eight patients were treated for rheumatoid arthritis, 1 was treated for cutaneous psoriasis, and 1 was treated for pyoderma gangrenosum. The median duration of TNF-alpha antagonist treatment at onset of infection was 38.5 weeks (range, 3-73 weeks). Eight patients were receiving concomitant treatment with corticosteroids, and 6 were receiving treatment with methotrexate. The relative risk of legionellosis when receiving treatment with a TNF-alpha antagonist, compared with the relative risk in France overall, was estimated to be between 16.5 and 21.0. We also report a second episode of confirmed legionellosis following the reintroduction of infliximab therapy.
Conclusions: L. pneumophila pneumonia is a potentially severe but curable infection that might complicate anti-TNF-alpha therapy. In patients receiving anti-TNF-alpha who develop pneumonia, legionellosis should be systematically investigated, and first-line antibiotic therapy should be efficient against L. pneumophila.