Reactive Arthritis Resulting From Postoperative Complications of Third Molar Extraction: A Case Report

The role of bacterial infections as potential triggers for chronic rheumatic diseases is well-documented. Oral infections such as periodontitis may play a particularly important role in the development of autoimmune diseases, with the oral cavity serving as a reservoir for pathogenic bacteria. These bacteria may trigger dysregulatory immune responses through mechanisms like molecular mimicry, whereby bacterial peptides resemble self-peptides. Genetic factors may also predispose individuals to specific autoimmune diseases, most notably human leukocyte antigen B27 (HLA-B27) in the case of ankylosing spondylitis as well as other rheumatic diseases. We present a case of a 23-year-old woman with reactive arthritis resulting from a postoperative infection. The patient presented with bilateral shoulder pain, decreased range of motion, worsening lower back pain, and mandibular pain at the site of a recent third molar extraction. Though initially diagnosed with rheumatoid arthritis, the patient experienced rapid and dramatic improvements following surgical treatment of the unresolved infection, demonstrating a causative or temporally related association between oral infections and chronic systemic autoimmune disease. This case provides useful evidence regarding causal mechanisms for the connections between chronic autoimmune diseases and oral bacterial infection, illustrating how oral infection may serve as a causative factor for reactive arthritis. We suggest that this implicates bacteria normally present in oral microflora as a potential source of the antigens involved in triggering systemic inflammation, especially those already associated with other autoimmune diseases, such as Klebsiella pneumoniae in the case of ankylosing spondylitis. Based on prior publications linking self-peptides with homologies in such bacteria, we speculate on mechanisms underlying this connection, with particular attention to molecular mimicry. Clinicians should be aware of the close connection between certain rheumatic diseases (such as reactive arthritis) and bacterial infection, particularly of the oral cavity; such awareness should inform strategies for treatment and prevention of arthritic disease.