Reactive Arthritis
Reactive arthritis is an unusual form of SpA that occurs following an infection, usually originating in the gastrointestinal or genitourinary systems, and most commonly affects young adults, both men and women. The infectious agents associated with this disease include Chlamydia trachomatis in the genitourinary tract and Salmonella, Shigella, Yersinia, or Campylobacter in the gastrointestinal tract. Other microbes, including Escherichia coli, Clostridium difficile, and Chlamydia pneumoniae have recently been added to the list of causative agents. HLA-B27 and genetics appear to be involved in susceptibility to developing reactive arthritis after an infection.
The arthritic symptoms typically have their onset from days to weeks after the antecedent infection. The arthritis is aseptic, as no microbes have been identified in the joints. Joint involvement is typically asymmetric and episodic, primarily affecting the knees and ankles. In addition to a preceding urethritis or diarrhea, extra-articular findings may include enthesitis (often of the knees and ankles), dactylitis of the fingers and toes (“sausage digits”), and sacroiliitis. Oral ulceration, nail pitting, and the skin eruptions of keratoderma blennorrhagicum (Fig 9-2) and erythema nodosum (Fig 9-3) can also occur. Ocular findings may be present in up to 40% of patients (see “Ophthalmic considerations”). Historically, the term Reiter syndrome was used to describe the clinical triad of arthritis, urethritis, and conjunctivitis. However, individuals with all 3 findings represent only a small subset of patients.
The disease is often episodic, and most patients go into remission within 2 years. Any underlying infection should be treated with appropriate antibiotics. In most patients, NSAIDs are effective in managing inflammation. For refractory symptoms, glucocorticoid injection into inflamed joints or, more rarely, the use of biologic agents is sometimes necessary.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.