[Clostridium difficile-associated diarrhea: causes and relationship to reactive arthritis].

We present a patient treated with methotrexate (MTX] for rheumatoid arthritis, in whom clostridium difficile-associated colitis has developed, without preceding antibiotic treatment. Two weeks later, the patient was admitted with knee arthritis. Reactive arthritis was diagnosed and treated successfully with the naproxen. The article discusses risk factors for Clostridium difficile-associated diarrhea [CDAD] other than antibiotics, and the relation of this pathogen to the development of reactive arthritis. It seems to be the first report of the association of MTX treatment with CDAD.