19th January 2024

Background 

Definition

Reactive arthritis is an inflammatory arthritis which occurs typically following a gastrointestinal or genitourinary infection. The infection may precede symptom onset by around 1 to 4 weeks. The classical triad of arthritis, urethritis and conjunctivitis, also known as Reiter’s syndrome, is frequently described but only occurs in a minority of patients.

Causes and pathophysiology

Reactive arthritis commonly affects young Caucasian adults. The syndrome is often subdivided into two groups depending on the underlying cause:

1. Post-enteric – associated with gram-negative bacteria such as Campylobacter (most common), Salmonella, Shigella, and Yersinia.
2. Post-venereal – associated with Chlamydia infection, Neisseria gonorrhoeae or human immunodeficiency virus (HIV).

Reactive arthritis associated with sexually transmitted infections is most commonly seen in men, whereas post-enteric arthritis has an equal sex incidence. The most frequent causative organism of reactive arthritis is Chlamydia trachomatis, with Chlamydia pneumoniae also being a known trigger. Bacterial DNA of causative organisms have been identified in the synovial tissue of patients presenting with reactive arthritis. A strong association with HLA B27 has been noted.