What are the typical presentation, common triggers, and first‑line management of reactive arthritis in adults?

Reactive Arthritis: Presentation, Triggers, and Management

Typical Clinical Presentation

Reactive arthritis presents as an acute asymmetric oligoarthritis of the lower limb joints (typically one knee or ankle) developing 2–4 weeks after a remote genitourinary or gastrointestinal infection. 1, 2

• The arthritis is characteristically subacute in onset, affecting large joints of the lower extremities in an asymmetric pattern (mono- or oligoarthritis). 3
• Approximately 25% of patients have asymptomatic triggering infections, making the diagnosis more challenging. 1
• Associated features include sacroiliitis, enthesitis, tenosynovitis, bursitis, and dactylitis (sausage digits). 2, 4
• Extra-articular manifestations are common: anterior uveitis, urethritis, conjunctivitis, and skin lesions such as keratoderma blennorrhagicum (pustular lesions on plantar surfaces). 2
• HLA-B27–positive patients develop more severe symptoms, more extra-articular features, and are more likely to present with complete Reiter's syndrome (arthritis, urethritis, conjunctivitis) compared with HLA-B27–negative patients. 3

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Common Triggering Infections

The most common bacterial triggers are Chlamydia trachomatis (urogenital), and enteric pathogens including Salmonella, Shigella, Yersinia, and Campylobacter jejuni. 1, 5, 2, 4

• Urogenital reactive arthritis is most often triggered by Chlamydia trachomatis. 1, 5
• Enteric (post-enteritic) reactive arthritis follows gastrointestinal infections with Yersinia, Salmonella, Shigella, Campylobacter jejuni, and possibly Clostridium difficile. 3, 4
• Diagnosis of the triggering infection is achieved by isolating the organism (stool cultures for enteric pathogens; ligase chain reaction for Chlamydia) or by serological testing when cultures are negative after arthritis onset. 1
• Serological tests are not standardized, and after arthritis develops, isolation of the organism becomes less likely. 1

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First-Line Management

Acute Symptomatic Treatment

NSAIDs are the cornerstone of initial therapy for acute reactive arthritis, combined with local measures such as arthrocentesis, cold application, and rest of the affected joint. 5, 3, 4

• NSAIDs should be used at the minimum effective dose for the shortest duration after evaluating gastrointestinal, renal, and cardiovascular risk. 5
• Intra-articular corticosteroid injections can provide rapid relief when one or two joints are predominantly affected. 5
• Systemic corticosteroids are reserved for patients with inflammatory symptoms resistant to NSAIDs. 4

Antibiotic Therapy for Chlamydia-Induced Reactive Arthritis

If Chlamydia trachomatis is isolated from the urogenital tract, treat the infection immediately with doxycycline 100 mg twice daily for 10–14 days, or erythromycin 500 mg four times daily for 10–14 days, or a single dose of azithromycin 1 g. 5

• The sexual partner must be treated concurrently to prevent reinfection. 5
• Prolonged antibiotic therapy (3 months) in Chlamydia-induced reactive arthritis without positive cultures may provide some benefit, but further studies are needed before this is routinely recommended. 5
• Antibiotics have no proven benefit in enteric forms of reactive arthritis, even when given for prolonged periods, despite detection of bacterial remnants and RNA in joint fluid. 5

Disease-Modifying Therapy for Chronic Reactive Arthritis (>6 Months)

For reactive arthritis persisting longer than 6 months, add sulfasalazine 2 g/day to continued NSAID therapy. 5, 4

• Sulfasalazine is moderately superior to placebo in placebo-controlled trials and is well tolerated. 5
• Other DMARDs (azathioprine, methotrexate, cyclosporine) can be tried in individual patients unresponsive to sulfasalazine, but no controlled studies support their use; the risk-benefit ratio must be carefully discussed with the patient. 5, 4
• In aggressive cases or when reactive arthritis evolves toward ankylosing spondylitis, TNF-α blockers may be effective. 4

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Prognosis and Long-Term Outcomes

The majority of patients have a self-limiting course lasting weeks to several months, but 20–25% develop chronic arthritis lasting more than 1 year. 5, 2

• About 25–50% of patients experience recurrent acute arthritis, depending on the triggering infection and possible new infections. 1
• Approximately 25% of patients progress to chronic spondyloarthritis of varying activity. 1
• HLA-B27 positivity serves as a prognostic indicator for more severe and chronic disease. 2, 3

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Critical Diagnostic Pitfalls

• In approximately 25% of cases, the triggering infection is asymptomatic, so a high index of suspicion and serological testing are essential. 1
• Reactive arthritis was initially characterized as sterile arthritis, but detection of metabolically active Chlamydia species in joint fluid has blurred the boundary between reactive and post-infectious arthritis. 1, 2
• No validated diagnostic criteria exist; diagnosis is primarily clinical, based on acute oligoarthritis of large joints developing 2–4 weeks after a remote infection. 1, 2
• HLA-B27 testing supports the diagnosis in the correct clinical context but is not diagnostic in isolation. 2