creation date: 2026-06-12 00:31
tags: Pathologies
Reactive Arthritis
Background
Definitions
Reactive arthritis refers to arthritis that arises following an infection, although pathogens cannot be cultured from the affected joints.
Etiology
A number of enteric or genitourinary infections can cause reactive arthritis. Common bacteria are:
Enteric bacteria
- Salmonella
- Shigella
- Yersinia
- Campylobacter
- C. difficile
Genital bacteria
- Chlamydia trachomatis
Pathogenesis
Following a mucosal infection, an aberrant immune response, driven partially by persistence of antigens within synovial tissue, causes synovial inflammation.
In addition to direct microbial antigens, molecular mimicry or other forms of activation of innate/adaptive immune pathways may explain reactive arthritis due to viral infections or vaccinations.
Clinical Presentation
Signs & Symptoms
Preceding infection
Common signs of enteric and genitourinary infections are:
- Diarrhea
- Urethritis
Musculoskeletal
Peripheral arthritis is characterized by:
- Acute onset
- Asymmetric oligoarthritis (typically lower extremities)
- May affect small joints
Other findings include:
- Enthesitis
- Dactylitis (sausage digits)
- Inflammatory low back pain
Extramusculoskeletal
- Ocular symptoms (conjunctivitis, anterior uveitis, episcleritis, keratitis)
- Genitourinary tract symptoms (dysuria, pelvic pain, urethritis, cervicitis, prostitis, salpingo-oophoritis, cystitis)
- Gastrointestinal symptoms (diarrhea)
- Oral lesions (painless mucosal ulcers)
- Skin changes (keratoderma blennorrhagica, erythema nodosum)
- Nail changes
- Genital lesions
- Cardiac manifestations (uncommon)
The classic triad for reactive arthritis for chlamydia is “can’t see, can’t pee, can’t climb a tree”:
- Conjunctivitis
- GU symptoms
- Arthritis
History & Physical Exam
Risk Factors
Diagnosis
Criteria
Diagnosis is made clinically based on characteristic MSK findings and exclusion of other causes of oligoarthritis, monoarthritis, or enthesitis.
Evidence of preceding infection supports the diagnosis but does not exclude the diagnosis if the causative pathogen is not identified.
Work-up
Laboratory findings may support the diagnosis but is not necessary for diagnosis.
- Stool sample (not used if diarrhea has resolved)
- Urine/genital swab if Chlamydia is suspected
- ESR/CRP - note, may not be elevated in some patients
- Synovial fluid (elevated WBC, neutrophil dominant) - nonspecific, like other inflammatory arthritis
Imaging is nonspecific.
Differential
Discussed separately.
Red Flags / Complications
Management
Treatment of Infection
Antibiotics are not routinely indicated for uncomplicated enteric infections. In general, diarrhea is self-limiting.
Patients (and their partner) with acute Chlamydia trachomatis infection should receive standard antimicrobial treatment.
- Doxycycline 100 mg BID x7 days
Treatment of Arthritis
As the disease is generally self-limited, treatment is symptomatic relief. Therapy follows stepwise escalation if inadequate:
- NSAIDs (eg. naproxen 500 mg BID)
- Intraarticular glucocorticoids
- Systemic glucocorticoids (eg. prednisone 20 mg daily)
DMARDs may be considered in cases in refractory arthritis to above therapy or chronic reactive arthritis.