Characterisation of Intestinal Microbiota of Patients With Spondyloarthritis or Rheumatoid Arthritis

This study looks at the gut microbiome (the community of bacteria living in the intestines) in patients with inflammatory joint diseases — either spondyloarthritis or rheumatoid arthritis — and compares it to healthy people. Researchers want to understand whether gut bacteria play a role in these conditions. **You may be eligible if...** - You are 18 or older - You have been diagnosed with spondyloarthritis or rheumatoid arthritis according to established medical criteria - You are covered by health/social insurance - You can sign the consent form - OR you are a healthy adult with no chronic disease (for the control group) **You may NOT be eligible if...** - You are unable to understand or consent to the study - You have another serious active condition (for healthy volunteers) Talk to your doctor to see if this trial is right for you.