Reactive Arthritis Associated With Helicobacter Pylori Infection Presenting as Treatment-Refractory Monoarthritis: A Case Report

Helicobacter pylori (H. pylori) is a prevalent gastric pathogen increasingly recognized as a potential trigger for extra-gastric inflammatory conditions. Despite this, its association with reactive arthritis (ReA) remains under-reported and is often overlooked in the differential diagnosis of seronegative arthritis. A 19-year-old female presented with a five-month history of persistent inflammatory monoarthritis of the left knee. The condition was refractory to non-steroidal anti-inflammatory drugs (NSAIDs), intra-articular corticosteroid injections, and conventional synthetic disease-modifying antirheumatic drugs (csDMARDs), including methotrexate and sulfasalazine. Clinical investigations revealed an inflammatory, aseptic synovial effusion, while serological markers - including antinuclear antibodies (ANA), rheumatoid factor (RF), and anticyclic citrullinated peptide (anti-CCP) - and human leukocyte antigen B27 (HLA-B27) were negative. A concurrent evaluation for dyspepsia identified an active H. pylori infection via a urea breath test. Following the discontinuation of all immunosuppressive therapy and the administration of a 10-day triple eradication regimen, the patient achieved complete and sustained clinical and biochemical remission, which was maintained at a three-month follow-up. This case underscores the importance of considering H. pylori as a causative agent in cases of unexplained, treatment-refractory monoarthritis. Systematic screening for H. pylori may identify a reversible infectious trigger, potentially preventing unnecessary long-term immunosuppression and biological therapy in young patients.