[Infection-induced reactive arthritis : etiopathogenesis, clinical spectrum, therapy].

Reactive arthritis is an inflammatory joint disease induced by a preceding, sometimes asymptomatic bacterial infection outside the joints. With an estimated prevalence of 40/100,000 inhabitants, the disease primarily affects adults between the ages of 20 and 40 years. The clinical presentation is typically characterized by monoarthritis to oligoarthritis of the lower extremities with possible accompanying enthesitis, bursitis, tenosynovitis, sacroiliitis, dactylitis and rare extra-articular manifestations. Because of the similar clinical symptoms and an association with HLA-B27, reactive arthritis is attributed to the spondyloarthropathies. Typical triggering pathogens are Chlamydia, Salmonella, Yersinia, Shigella and Campylobacter. In about 20% of the cases the usually self-limiting disease becomes chronic. The pathogenesis is not yet understood in detail but it is currently assumed that the intracellular persistence of the pathogen causes an immune reaction resulting in arthritis. Common international diagnostic criteria do not yet exist; therefore the diagnosis is made largely on the basis of clinical findings, medical history and the direct and/or indirect pathogen detection. Several therapeutic options are used to treat reactive arthritis. Ongoing extra-articular infections, with the exception of enteritis should be treated with antibiotics. Besides symptom-orientated treatment of acute arthritis, in prolonged and chronic reactive arthritis an immunomodulatory therapy with steroids, sulfasalazine or methotrexate is used. The role of long-term antibiotic therapy for eradication of persistent intra-articular pathogens in chronic cases is the subject of current research.