Reiter's Syndrome

Content of This Page

1- Introduction

2- Causes

3– Pathophysiology

4- Signs & Symptoms

5- Investigations & Lab Results

6- Complications

7- Treatment

Introduction

Reiter’s syndrome, now more commonly referred to as reactive arthritis, is a type of seronegative spondyloarthropathy that occurs as a post-infectious autoimmune response, typically following certain gastrointestinal or genitourinary infections. It is most often associated with bacterial pathogens such as Chlamydia trachomatis, Shigella, Salmonella, Yersinia, and Campylobacter.

The condition is characterized by the classic triad of arthritis, urethritis, and conjunctivitis, although not all patients present with all three components. Symptoms usually develop 1 to 4 weeks after the initial infection. It most commonly affects young adults, especially males, and is strongly associated with the HLA-B27 gene.

Reactive arthritis is considered sterile, meaning that the joint inflammation occurs without direct bacterial infection of the joint space. The exact mechanism is thought to involve molecular mimicry and immune system activation triggered by the initial infection.

© image from Wikimedia Commons

Causes

1. Gastrointestinal Infections (Enteric):

These infections usually precede arthritis by 1–4 weeks and involve foodborne or fecal-oral transmission.

  • Shigella (especially S. flexneri)

  • Salmonella (S. enteritidis, S. typhimurium)

  • Yersinia enterocolitica

  • Campylobacter jejuni

2. Genitourinary Infections:

Sexually transmitted pathogens are also common triggers.

  • Chlamydia trachomatis

  • Ureaplasma urealyticum (less common)

3. Risk Factors and Associations:

  • HLA-B27 positivity (strong genetic predisposition)

  • Male gender

  • Age 20–40 years

  • History of recent dysentery or urethritis

Pathophysiology

1. Triggering Infection

  • A bacterial infection (e.g., Shigella, Chlamydia) occurs in the gut or urogenital tract.

  • Bacterial components (such as lipopolysaccharides) persist in the body, especially in the synovial tissue.

2. Immune System Activation

  • The immune system recognizes these bacterial antigens and becomes hyperactive.

  • In genetically predisposed individuals (especially HLA-B27 positive), this immune response is misdirected, leading to cross-reactivity with host tissues (molecular mimicry).

3. Inflammatory Cascade

  • Cytokines (e.g., TNF-α, IL-1, IL-6) are released.

  • These inflammatory mediators attract immune cells to joints, eyes, and urogenital tissue.

  • This results in non-infectious inflammation of:

    • Synovial membranes (arthritis)

    • Urethra (urethritis)

    • Conjunctiva (conjunctivitis)

4. Joint Involvement

  • Usually affects large joints of the lower limbs (asymmetric oligoarthritis).

  • May also cause enthesitis (inflammation at tendon insertion points) and sacroiliitis.

© image from Wikimedia Commons

Signs & Symptoms

1. Musculoskeletal (Arthritis)

  • Asymmetric oligoarthritis (affecting fewer than 5 joints)

  • Mainly involves lower limb joints (knees, ankles, toes)

  • Dactylitis (“sausage digits”)

  • Enthesitis (pain at tendon/ligament insertions, e.g., Achilles tendon)

  • Sacroiliitis or low back pain in some cases

2. Genitourinary (Urethritis/Cervicitis)

  • Dysuria (painful urination)

  • Urethral discharge in males

  • Cervicitis or vaginal discharge in females

  • Prostatitis or pelvic pain

3. Ocular

  • Conjunctivitis (mild, red eyes, tearing)

  • Uveitis (painful, red eye with blurred vision – more serious)

4. Gastrointestinal (if post-enteric)

  • History of recent diarrhea or dysentery

  • Abdominal pain or mild cramping (preceding arthritis)

5. Mucocutaneous and Skin

  • Keratoderma blennorrhagica: thick, scaly skin lesions on soles or palms

  • Circinate balanitis: painless ulcers on glans penis

  • Oral ulcers (painless)

6. Systemic Symptoms

  • Low-grade fever

  • Fatigue

  • Weight loss in prolonged disease

Investigations & Lab Results

1. Inflammatory Markers

  • ESR: Elevated

  • CRP: Elevated
    → Indicate systemic inflammation

2. HLA-B27 Testing

  • Often positive (in ~50–80% of cases)
    → Associated with more severe or chronic disease

3. Infectious Workup

  • Stool culture: May detect organisms like Shigella, Salmonella, Yersinia, Campylobacter

  • Urine PCR or swab: To detect Chlamydia trachomatis

  • Serology: Sometimes used to detect past infections

4. Rheumatologic Markers

  • Rheumatoid Factor (RF): Negative (helps rule out RA)

  • ANA: Usually negative
    → Reiter’s is a seronegative arthritis

5. CBC

  • May show leukocytosis or mild anemia of chronic disease

-Imaging

1. X-ray of affected joints

  • Early: Usually normal

  • Later: May show joint space narrowing, periostitis, or enthesopathy

2. Sacroiliac joint imaging (X-ray or MRI)

  • May show sacroiliitis in chronic or HLA-B27 positive patients

-Synovial Fluid Analysis

  • Inflammatory picture:

    • High WBC count

    • Sterile (no bacteria)
      → Important to rule out septic arthritis

Complications

  • Chronic or recurrent arthritis

  • Joint deformities or disability

  • Enthesitis and ankylosis (especially in spine/SI joints)

  • Recurrent uveitis → vision impairment

  • Aortic root involvement → aortic regurgitation

  • Cardiac conduction defects (e.g., AV block)

  • Chronic mucocutaneous lesions (e.g., keratoderma blennorrhagica)

  • Circinate balanitis

  • Chronic prostatitis → potential infertility

  • Psychological impact (depression, reduced quality of life)

Treatment

1. General Measures

  • Rest during acute flare-ups

  • Physical therapy to maintain joint mobility and prevent stiffness

  • Avoid activities that worsen symptoms

2. Pharmacological Treatment

  • NSAIDs (Nonsteroidal anti-inflammatory drugs)
    First-line for pain and inflammation relief.

  • Glucocorticoids

    • Local (intra-articular) injections for persistent joint inflammation.

    • Systemic steroids in severe or refractory cases (short-term use).

  • Disease-Modifying Anti-Rheumatic Drugs (DMARDs)
    Used if symptoms persist beyond 6 months or with chronic arthritis.
    Examples: Sulfasalazine, Methotrexate.

  • Antibiotics

    • Treat initial infection if still active (e.g., Chlamydia).

    • Antibiotics are not effective once reactive arthritis develops.

3. Ocular Treatment

  • Topical corticosteroids or other agents for conjunctivitis/uveitis, managed by an ophthalmologist.

4. Other Considerations

  • Treatment of genitourinary symptoms (urethritis/cervicitis).

  • Counseling and psychological support if needed.

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