Reactive Arthritis

Overview

Reactive arthritis, formerly known as Reiter's syndrome, is an inflammatory condition that typically develops 1-4 weeks after an infection. The condition is characterized by inflammation of the joints (arthritis), eyes (conjunctivitis or uveitis), and urinary tract (urethritis). This triad of symptoms led to its previous name, though not all patients experience all three components.

The condition affects approximately 30-40 per 100,000 people, with young adults between 20 and 40 years of age being most commonly affected. Men are more likely to develop reactive arthritis following sexually transmitted infections, while the gender distribution is more equal when the condition follows gastrointestinal infections.

Reactive arthritis is considered a type of spondyloarthropathy, a family of inflammatory rheumatic diseases that includes ankylosing spondylitis and psoriatic arthritis. While the initial trigger is an infection, the arthritis itself is not infectious and cannot be spread from person to person. Most cases resolve within 3-12 months, though some individuals may experience chronic symptoms or recurrent episodes.

Symptoms

Reactive arthritis typically presents with a characteristic pattern of symptoms that develop days to weeks after an initial infection. The severity and combination of symptoms can vary significantly between individuals.

Joint Symptoms

• Hip pain - Often affecting one or both hips with inflammatory characteristics
• Knee lump or mass - Swelling and fluid accumulation in the knee joint
• Joint pain - Typically affecting large joints asymmetrically
• Joint swelling - Particularly in knees, ankles, and feet
• Morning stiffness lasting more than 30 minutes
• Lower back pain and stiffness
• Heel pain (enthesitis)
• Swollen fingers or toes ("sausage digits")

Urogenital Symptoms

• Painful urination (dysuria)
• Increased urinary frequency
• Urethral discharge
• Prostatitis in men
• Cervicitis in women

Eye Symptoms

• Red eye (conjunctivitis)
• Eye pain
• Light sensitivity (photophobia)
• Blurred vision
• Excessive tearing

Other Symptoms

• Skin rashes, including keratoderma blennorrhagicum
• Mouth ulcers
• Nail changes (thickening, pitting)
• Fatigue
• Low-grade fever
• Weight loss

The arthritis typically affects the lower extremities asymmetrically, with the knees, ankles, and feet being most commonly involved. Inflammation at tendon insertion sites (enthesitis) is a characteristic feature that helps distinguish reactive arthritis from other forms of arthritis.

Causes

Reactive arthritis develops as an abnormal immune response to certain bacterial infections. The immune system, while fighting the infection, mistakenly attacks healthy tissue in the joints and other organs. The exact mechanism is not fully understood, but involves both genetic susceptibility and environmental triggers.

Common Triggering Infections

Gastrointestinal Infections

• Salmonella: Often from contaminated food
• Shigella: Causes bacterial dysentery
• Yersinia: Found in contaminated food and water
• Campylobacter: Common cause of food poisoning
• Clostridium difficile: Can occur after antibiotic use

Genitourinary Infections

• Chlamydia trachomatis: The most common trigger in sexually acquired cases
• Ureaplasma urealyticum: Another sexually transmitted organism
• Mycoplasma genitalium: Less common but recognized trigger

Pathophysiology

The development of reactive arthritis involves several mechanisms:

• Molecular mimicry: Bacterial antigens resemble host proteins, causing cross-reactive immune responses
• Bacterial persistence: Bacterial components may persist in joints despite clearance of the infection
• Aberrant immune response: Genetically susceptible individuals mount an exaggerated inflammatory response
• HLA-B27 association: This genetic marker is present in 50-80% of patients and increases susceptibility

Risk Factors

Several factors increase the likelihood of developing reactive arthritis following an infection. Understanding these risk factors helps identify individuals who may need closer monitoring after infections.

Genetic Factors

• HLA-B27 positivity: Increases risk 50-fold
• Family history of spondyloarthropathies
• Certain ethnic backgrounds (higher in Northern Europeans)

Demographic Factors

• Age: Most common between 20-40 years
• Gender: Men more likely after STIs, equal risk after GI infections
• Sexual activity: Higher risk with multiple partners

Environmental Factors

• Exposure to triggering bacteria
• Poor sanitation or food handling
• Travel to areas with endemic infections
• Immunosuppression
• HIV infection (increases severity)

Diagnosis

Diagnosing reactive arthritis can be challenging as there is no single definitive test. The diagnosis is based on clinical presentation, history of recent infection, and exclusion of other conditions. A thorough evaluation is essential to confirm the diagnosis and assess disease severity.

Clinical Criteria

Diagnosis typically requires:

• Inflammatory arthritis developing within 1-4 weeks of infection
• Evidence of preceding infection (clinical or laboratory)
• Exclusion of other causes of arthritis
• Characteristic pattern of joint involvement

Laboratory Tests

• Inflammatory markers: Elevated ESR and CRP
• HLA-B27 testing: Positive in 50-80% of cases
• Synovial fluid analysis: Shows inflammatory changes, sterile culture
• Microbiological tests: Stool culture, urogenital swabs, serology
• Autoantibody tests: Usually negative (helps exclude other conditions)
• Complete blood count: May show mild anemia

Imaging Studies

• X-rays: May show soft tissue swelling, joint effusions
• MRI: Detects early inflammatory changes, enthesitis
• Ultrasound: Useful for detecting synovitis and enthesitis
• CT scan: Sometimes used for sacroiliac joint assessment

The diagnosis often involves ruling out other conditions such as rheumatoid arthritis, psoriatic arthritis, gout, and septic arthritis. A detailed sexual and travel history is important for identifying potential triggering infections.

Treatment Options

Treatment of reactive arthritis aims to manage symptoms, reduce inflammation, treat any ongoing infection, and prevent chronic disease. The approach is individualized based on symptom severity, affected organs, and presence of triggering infections.

Pharmacological Treatment

First-Line Medications

• NSAIDs: Indomethacin, naproxen, or diclofenac for pain and inflammation
• Corticosteroid injections: For severely affected joints
• Antibiotics: If active infection is present (particularly for Chlamydia)

Second-Line Medications

• Systemic corticosteroids: For severe or widespread disease
• Sulfasalazine: Traditional DMARD for persistent symptoms
• Methotrexate: For chronic or severe cases

Biologic Therapies

• TNF inhibitors: Etanercept, infliximab for refractory cases
• IL-17 inhibitors: Emerging option for severe disease

Non-Pharmacological Treatment

• Physical therapy: Maintains joint function and muscle strength
• Occupational therapy: Helps with daily activities
• Rest during acute flares: Balanced with gentle exercise
• Cold/heat therapy: For symptomatic relief
• Orthotics: For enthesitis and foot problems

Management of Extra-Articular Manifestations

• Conjunctivitis: Topical corticosteroids, artificial tears
• Uveitis: Requires urgent ophthalmology referral
• Skin lesions: Topical corticosteroids or keratolytics
• Urethritis: Antibiotics if infection present

Long-Term Management

• Regular monitoring for disease activity
• Cardiovascular risk assessment
• Bone density monitoring if on long-term corticosteroids
• Patient education about triggers and prevention
• Psychological support for chronic cases

Prevention

While not all cases of reactive arthritis can be prevented, reducing exposure to triggering infections and prompt treatment of infections can lower the risk. Prevention strategies focus on avoiding infections and early intervention.

Preventing Gastrointestinal Infections

• Food safety: Proper food handling, cooking, and storage
• Hand hygiene: Regular handwashing, especially before eating
• Safe water: Avoid contaminated water sources
• Travel precautions: Care with food and water in endemic areas
• Kitchen hygiene: Clean surfaces and utensils thoroughly

Preventing Sexually Transmitted Infections

• Safe sex practices: Consistent condom use
• Regular STI screening: For sexually active individuals
• Partner notification: If infection is diagnosed
• Complete treatment: Of any diagnosed STIs

Secondary Prevention

• Early treatment of triggering infections
• Monitoring high-risk individuals (HLA-B27 positive)
• Prompt medical attention for arthritis symptoms after infections
• Long-term antibiotic therapy in selected cases

When to See a Doctor

Early medical evaluation is important for proper diagnosis and treatment of reactive arthritis. Prompt intervention can prevent complications and reduce the risk of chronic disease.

Seek Immediate Medical Attention If:

• Severe eye pain or vision changes (possible uveitis)
• High fever with joint swelling
• Inability to bear weight on affected joints
• Signs of severe dehydration from diarrhea
• Chest pain or shortness of breath

Schedule an Appointment If You Experience:

• Joint pain or swelling after recent infection
• Persistent urinary symptoms
• Recurring eye redness or irritation
• Unexplained skin rashes
• Heel pain or foot swelling
• Lower back pain with morning stiffness

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