Sexually Associated Reactive Arthritis (SARA); Post-infectious STI arthritis

Valeria Fabre, M.D.


  • The mechanism of SARA pathogenesis is not wholly known. This appears to be due to an immune response to urogenital organisms or the persistence of the organism or antigenic debris in synovial tissue.
    • Chlamydia trachomatis (CT): organism most strongly linked to SARA.
      • Identified in 35-70% of cases using non-nucleic acid amplification techniques.
      • When CT is the underlying cause, an aberrant form with the repressed synthesis of the major outer membrane protein and active production of heat shock protein appears, contributing to the inflammatory response.
    • Neisseria gonorrheae: linked to up to 16% of cases, distinct from gonococcal arthritis.
    • Ureaplasma urealyticum and Mycoplasma genitalium are linked to a few cases, a minor cause of SARA.
  • A causal role for other genital tract pathogens is unclear (there are cases of reactive arthritis due to Shigella).

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Last updated: March 21, 2023