Makindo Medical Notes

Related Subjects: |Monoarticular arthritis |Polyarticular arthritis |Seronegative Spondyloarthropathies |Ankylosing spondylitis |Enteropathic Spondyloarthritis |Reactive Arthritis |Dermatomyositis |Polyarteritis nodosa |Osteoporosis |Rheumatoid Arthritis |Systemic Sclerosis (Scleroderma) |Rheumatology Autoantibodies |Overlap Syndrome

♻️ Reactive arthritis is an infection-induced systemic illness characterised by inflammatory synovitis in which no viable microorganisms can be cultured. 🧪 It is a seronegative spondyloarthritis (RF negative).

📘 About

• Formerly known as Reiter’s syndrome (arthritis, conjunctivitis, urethritis/cervicitis).
• Triggered by a preceding GU infection (e.g. Chlamydia) or GI infection (e.g. Salmonella, Shigella).
• Occurs in genetically predisposed individuals (often HLA-B27 positive).

🧬 Aetiology

• Post-infectious autoimmune reaction — cross-reactivity between pathogen antigens and host tissues.
• Synovial fluid is sterile despite inflammatory response.
• Extra-articular features are common.

🦠 Triggering Infections

• Gastrointestinal: Salmonella, Yersinia, Campylobacter, Shigella.
• Sexually transmitted: Chlamydia trachomatis, Ureaplasma urealyticum.

🩺 Clinical Features

• Arthritis: Asymmetrical inflammatory oligo/monoarthritis of lower limbs (knees, ankles, feet, hips).
• Enthesitis: Achilles tendonitis, plantar fasciitis.
• Dactylitis: “Sausage toe” appearance due to MTP synovitis.
• Eye: Conjunctivitis, anterior uveitis.
• Skin & mucosa: Oral ulcers, circinate balanitis, keratoderma blennorrhagicum (pustular rash on soles), nail dystrophy, erythema nodosum.
• Cardiac: Aortitis, conduction defects (similar to ankylosing spondylitis).

📖 Reiter’s Syndrome (classic triad)

• Arthritis
• Conjunctivitis
• Urethritis / cervicitis
• ⚠️ Historically described in WWI soldiers with venereal disease or dysentery, but now considered clinically less useful as a strict definition.

🔬 Investigations

• Inflammatory markers: ↑ CRP, ESR, WCC (non-specific).
• Synovial fluid: Sterile, neutrophil-rich.
• Microbiology: Stool culture (Salmonella, Campylobacter, etc.), urine/urethral swabs (Chlamydia, Gonorrhoea).
• Serology: Rheumatoid factor negative, ANA negative.
• Consider HLA-B27 testing for prognosis/association.

💊 Management

• General: Bed rest during acute flares; physiotherapy for joint mobility.
• NSAIDs: First-line for pain and inflammation.
• Corticosteroids: Intra-articular injections for persistent monoarthritis.
• DMARDs: Sulfasalazine, methotrexate in resistant or chronic cases.
• Biologics: Anti-TNF agents (etanercept, infliximab) for refractory disease.
• Antibiotics: Only for active Chlamydia infection — not helpful once arthritis is established.

📚 References

• Aetiology and pathogenesis of reactive arthritis: role of HLA-B27

Cases — Reactive Arthritis

• Case 1 — Post-infectious triad 💩👀🦵: A 28-year-old man presents 3 weeks after an episode of dysenteric diarrhoea (Shigella). He has acute asymmetric arthritis of the right knee, conjunctivitis, and urethritis. Diagnosis: classic reactive arthritis (Reiter’s syndrome). Managed with NSAIDs and physiotherapy.
• Case 2 — Chlamydia-associated 🦠: A 32-year-old man presents with heel pain, dactylitis of the second toe, and urethral discharge. History: unprotected intercourse 6 weeks ago. Urine PCR positive for Chlamydia trachomatis. Diagnosis: chlamydia-triggered reactive arthritis. Managed with antibiotics for infection and NSAIDs for arthritis.
• Case 3 — Chronic/reactive course ⏳: A 40-year-old woman presents with 6 months of persistent arthritis affecting the ankles and lower back after an episode of Salmonella gastroenteritis. Exam: enthesitis at Achilles tendon insertion and sacroiliac tenderness. HLA-B27 positive. Diagnosis: chronic reactive arthritis. Managed with DMARDs (sulfasalazine) after failure of NSAIDs.

Teaching Point 🩺: Reactive arthritis is an aseptic arthritis following GU or GI infection. Classic triad = arthritis, urethritis, conjunctivitis. It is part of the seronegative spondyloarthropathies, often HLA-B27 associated. Usually self-limiting but may become chronic.