Septic arthritis with Listeria monocytogenes during low-dose methotrexate.

We describe a 22-year-old female with systemic lupus erythematosus and lymphopenia, who developed septic arthritis of the right knee with Listeria monocytogenes type 1/2 A, whilst on low-dose methotrexate (MTX). So far, septic arthritis due to this microorganism has been reported in two other patients treated with low-dose MTX, one having rheumatoid arthritis and the other psoriatic arthritis. No reports exist on patients treated with other cytotoxic antirheumatic therapies.