reactive arthritis

Question 1

definition of reactive arthritis

Answer 1

An inflammatory arthritis that occurs after exposure to certain gastrointestinal and genitourinary infections. The classical triad of post-infectious arthritis, non-gonococcal urethritis, and conjunctivitis is frequently described but found only in a minority of cases and not required for diagnosis.[1] This triad of symptoms was described by Hans Reiter in 1916. However, the term ‘Reiter’s syndrome’ has fallen out of favour because of his ties to the Nazi Party and medical experiments on concentration camp prisoners.[2] ReA belongs to the family of spondyloarthropathies, which share similar clinical, radiographic, and laboratory features that include spinal inflammation and an association with HLA-B27. They include psoriatic arthritis, ankylosing spondylitis, arthritis related to inflammatory bowel disease, and undifferentiated spondyloarthropathy.

Question 2

associated organisms

Answer 2

The bacteria associated with reactive arthritis (ReA) are common causes of venereal disease and infectious dysentery.
The most commonly implicated bacterial species are Chlamydia (MOST COMMON), Salmonella, Campylobacter, Shigella, and Yersinia species, although ReA has been described after many other bacterial infections.

Question 3

risk factors

Answer 3

• male
• HLA-B27 positive genotype
• preceding chlamydia or GI infection
  (Clinical symptoms typically begin within 1 to 4 weeks after the onset of infection. The latency in developing arthritis associated with post-chlamydial infections may be longer than that associated with post-dysenteric infections.)

Question 4

other diagnostic factors

Answer 4

• peripheral arthritis
• axial arthritis
• constitutional symptoms (fever, fatigue, weight loss)
• enthesitis (inflammation at sites where tendons insert into bones. Common sites include the Achilles’ tendon and plantar fascia at the calcaneus, which manifest as heel pain)

Question 5

investigations

Answer 5

1st investigations:

• ESR, CRP => eelevated
• ANA, RF => ussually neg.
• urogential and stool cultures => looking for bacteria
• plain x rays => sacroiliitis or enthesopathy in chronic ReA
• arthrocentesis with synovial fluid analysis (check for crytals to rule out gout/pseudogout)

others:

• HLA-B27
• MRI => sacroiliitis or enthesopathy
• nucleic amplification tests (indicated with asymptomatic suspected sexually acquired ReA => may be positive for Chlamydia trachomatis or Neisseria gonorrhoeae)