Listeria monocytogenes infection in a patient treated with methotrexate for rheumatoid arthritis.

We describe a patient with rheumatoid arthritis who developed bacteremia from Listeria monocytogenes after treatment with low dose oral pulse methotrexate. We discuss possible immunologic mechanisms for susceptibility to Listeria infections. As the elderly population increases with more frequent use of immunosuppressive medications, clinical suspicion must be maintained to correctly diagnose and treat infections such as Listeria.