Clinically silent infections in patients with oligoarthritis: results of a prospective study.

Oligoarticular synovitis of undetermined origin can closely resemble an incomplete form of reactive arthritis/Reiter's syndrome. Eighty three patients with oligoarthritis of undetermined origin were studied prospectively to identify asymptomatic infections potentially triggering the inflammatory response in the synovial fluid. At the time of initial evaluation, 57 (69%) of the patients with oligoarthritis and 4/20 (20%) of the control subjects were carriers of clinically silent infections. Evidence for persistent or prior chlamydial infections was frequently and exclusively found in the study group (30/83 (36%) patients v no controls), whereas undetected urogenital infections with mycoplasma were present in nine (11%) patients and four (20%) controls. Eleven (13%) of the patients carried cellular and humoral responses to Borrelia burgdorferi. The HLA-B27 haplotype represented a major risk factor for the development of oligoarthritis but not for development of sacroiliitis. Re-evaluation after one year showed that the course and outcome of the oligoarticular disease did not correlate with a specific infectious organism and were not affected by antibiotic treatment sufficient to treat the carrier state.