Reactive arthritis (ReA)
Reactive arthritis (ReA) is a sterile, inflammatory arthritis that is typically preceded by a gastrointestinal or genitourinary infection occurring 1 to 4 weeks previously.
Similar to other spondyloarthropathies, patients with ReA are more likely to be human leukocyte antigen-B27 (HLA-B27) positive, which portends a worse prognosis and more joint and extraarticular manifestations.
Long-term (3 to 6 months) antibiotics may help Chlamydia-induced ReA but does not affect the course of ReA associated with enteric pathogens.
Over 50% of patients have a self-limited course lasting 2 to 6 months, 30% have recurrent episodes, and 10% to 20% have a chronic course requiring immunosuppressive therapy.
As originally described in 1916, Reiter’s syndrome is the clinical triad of conjunctivitis, nongonococcal urethritis, and arthritis following an infectious dysentery. Reiter’s syndrome, a term no longer used, is now considered to be a form of ReA because two thirds of patients do not have all three features of this triad.
Iinfectious agents “causing” ReA:
Chlamydia trachomatis, Ureaplasma urealyticum
Salmonella typhimurium, Salmonella enteritidis, Salmonella Heidelberg, Salmonella choleraesuis
Shigella flexneri, Shigella dysenteriae, Shigella sonnei
Yersinia enterocolitica, Yersinia pseudotuberculosis
Streptococcus (post-Streptococcal ReA)
Note: In 40% of ReA patients an infectious agent cannot be identified. Urine PCR for Chlamydia and stool cultures may be helpful in patients with urethritis or diarrhea, respectively. Serologic tests for Chlamydia, Salmonella, and Yersinia can be done depending on the suspected inciting agent.