In the pathogenesis of spondyloarthropathies, infection and gut inflammation are the most important external triggering factors. Early antimicrobial therapy to treat urethritis caused by Chlamydia trachomatis is effective in preventing a recurrent reactive arthritis. When the arthritis appear, a short term conventional antimicrobial therapy is unable to modify its course. In acute chlamydia arthritis, patients benefit from a prolonged (3-month) treatment with tetracycline, while such a treatment has not proved to be effective in enteroarthritis or in chronic forms of reactive arthritis. The role of sulfasalazine in the treatment of patients with spondyloarthropathies is controversial. It might modify the disease course during acute and chronic reactive arthritis, and is working for patients with ankylosing spondylitis, especially patients with peripheral arthritis. Data showing an effect of sulfasalazine in the prevention of chronic spondyloarthropathy or in modification of the long-term prognosis of ankylosing spondylitis are, however, lacking.