Reactive arthritis

Question 1

What are the causes of reactive arthritis?

Answer 1

Sterile synovitis, occurs days- weeks following:

• GI infection – specifically Salmonella, Shigella, Campylobacter
• GU infection – Chlamydia, Ureaplasma

**if suspecting reactive arthritis but no obvious GI/GU symptoms, do urine PCR to look for chlamydia etc

In 10-25% of cases, the triggering infection may be asymptomatic, esp in Chlamydia infection

Increased susceptibility to reactive arthritis in HLA B27 due to:

• TCR repertoire selection
• Molecular mimicry causing autoimmunity against HLA-B27 and/or other self-antigens
• Presentation of bacteria-derived peptides to T-cells

Question 2

What are the clinical features of reactive arthritis?

Answer 2

Classically triad of conjunctivitis, urethritis, arthritis (can’t see, can’t pee, can’t climb a tree)

MSK

• Acute, asymmetrical, LL arthritis (may be PC if infection is mild/asymptomatic)
• 30% patients also p/w: Enthesitis (plantar fasciitis, Achilles tendonosis), Sacroilitis, Dactylitis, Spondylitis (causing IBP)

Skin

• Circinate balanitis (glans penis)
• uncircumcised: painless superficial ulcer
• Circumcised: raised, red and scaly lesion
• Keratoderma blennorrhagica: painless, red, often confluent plaques and pustules on feet and hands (histo similar to pustular psoriasis)
• Nail dystrophy

Eye

• Sterile conjunctivitis (30%)
• Acute anterior uveitis (severe, relapsing disease)

Question 3

What are the investigations to be performed for reactive arthritis?

Answer 3

Clinical hx & Sexual Hx and Chronology of symptoms

Demonstration of triggering infection
- Stool culture in GI infection
- Chlamydia PCR – chlamydia is a parasite hence unable to be cultured!
- Urine Culture
-
Blood tests (FBC, ESR, CRP)
-
Joint X Ray

Joint Aspiration – to show aseptic arthritis

HLA-B27 – checking it may be helpful but is controversial and not necessary

Question 4

What is the management for reactive arthritis?

Answer 4

Mx of the persistent triggerring infection

• C/s and abx – TRO Septic Arthritis
• ↑ESR and CRP
• Stool c/s if diarrhea
• Infectious serology
• Screen sexual partners

Mx of arthritis
- Pain: NSAIDs and corticosteroids (local/oral)
- Severe and persistent disease:
o 1st line: MTX/ SSZ
o 2nd line: TNF-α blockers (rarely needed)