Can Chlamydia (Chlamydia trachomatis) cause septic arthritis?

Chlamydia and Septic Arthritis

Yes, Chlamydia trachomatis can cause a form of inflammatory arthritis, specifically reactive arthritis, but it does not cause true septic arthritis. 1, 2

Chlamydia-Associated Arthritis

Reactive Arthritis vs. Septic Arthritis

• Chlamydia trachomatis is associated with reactive arthritis (formerly known as Reiter's syndrome), which is different from septic arthritis 2
• Reactive arthritis is characterized by sterile joint inflammation triggered by infection elsewhere in the body, while septic arthritis involves direct infection of the joint 1, 2
• Chlamydia-induced reactive arthritis is part of the spondyloarthritides group of conditions 3

Pathophysiology

• Chlamydia trachomatis can disseminate from the initial genital infection site to establish persistent viable organisms in synovial tissue 2
• The bacteria can persist in a unique state that allows them to evade the immune system while triggering ongoing inflammation 4
• This persistence contributes to chronic inflammation in the joints without actual bacterial replication within the joint fluid (which would characterize true septic arthritis) 2

Clinical Presentation

• Reactive arthritis typically develops 1-4 weeks after a genitourinary infection with Chlamydia trachomatis 3
• It primarily affects young adults and is more common in men 5
• The classic triad includes:
  • Arthritis (typically asymmetric, affecting knees, ankles, and feet)
  • Urethritis
  • Conjunctivitis 5, 3
• Approximately 30% of patients with Chlamydia-induced reactive arthritis develop a chronic course 2

Diagnosis

• Diagnosis requires evidence of present or past Chlamydial infection, typically through PCR testing of first-void urine or genital swabs 6
• Joint fluid analysis in reactive arthritis shows inflammatory cells but no bacteria (unlike septic arthritis where bacteria would be present) 4
• Chlamydia pneumoniae can also trigger reactive arthritis, though less frequently than Chlamydia trachomatis 1, 2

Treatment

• Management includes:
  • Antibiotic therapy to eradicate the triggering infection (typically doxycycline or azithromycin) 6
  • NSAIDs for symptomatic relief 3
  • Disease-modifying antirheumatic drugs (DMARDs) for persistent symptoms 6
  • In severe cases, biological agents may be required 6

Important Clinical Considerations

• Chlamydia-induced reactive arthritis is likely underdiagnosed in clinical practice 3
• Even asymptomatic chlamydial infections can trigger reactive arthritis 3
• Recent evidence suggests that long-term combination antimicrobial treatment may help eradicate persistent infection and improve symptoms in chronic cases 2
• Screening for Chlamydia should be considered in young adults presenting with new onset inflammatory arthritis, especially with urogenital symptoms 5, 3

Common Pitfalls

• Failing to consider Chlamydia as a cause of arthritis, especially in patients without obvious genital symptoms 3
• Misdiagnosing Chlamydia-induced reactive arthritis as another form of inflammatory arthritis 3
• Not testing for Chlamydia in patients with unexplained inflammatory arthritis 6
• Inadequate treatment duration for the underlying Chlamydial infection 2