Impact of urogenital and enterocolitic infections on the onset and evolution of ankylosing spondylitis and psoriatic arthritis

Introduction : Infections such as Chlamydia trachomatis and Yersinia enterocolitica are recognized triggers of reactive arthritis, but their role in chronic spondyloarthritis (SpA)—including ankylosing spondylitis (AS) and psoriatic arthritis (PsA)—remains incompletely defined. Aim : To evaluate the potential role of selected urogenital and enterocolitic infections in the onset and clinical evolution of AS and PsA. Materials and methods : This prospective observational study included 1202 patients (709 PsA, 493 AS) followed between 2019 and 2025. Clinical subtypes, disease activity, and imaging features were assessed alongside multiplex PCR and serological screening for C. trachomatis , Mycoplasma spp., Ureaplasma spp., and Y. enterocolitica . Comparisons were made between infection-triggered and idiopathic cases. Results : Infection was found in 6.2% of PsA and 8.1% of AS patients, which was slightly higher than the control group. Infection-triggered cases presented more often with acute onset, oligoarthritis, and peripheral joint involvement (notably in AS, p =0.002). Over time, PsA showed a shift from oligoarticular to polyarticular and axial forms; axial PsA increased from 2.1% to 21.1% in 2 years. Radiographic and treatment outcomes were comparable between groups. A minority of infection-triggered cases showed remission following antibiotic therapy. Conclusions : Urogenital and enterocolitic infections may precipitate SpA in a small subset of genetically susceptible individuals, particularly with HLA-B27. While long-term disease trajectories resemble idiopathic forms, early identification of infectious triggers may aid in personalized management strategies. Further research is needed to clarify their role in chronic disease propagation and treatment responsiveness.