Which bacteria is commonly implicated in enteropathic arthropathies?

• A. Staphylococcus aureus
• B. Streptococcus pneumoniae
• C. Escherichia coli
• D. Shigella

Answer: (D)

Enteropathic arthropathies are a form of reactive arthritis that follows certain gut infections, where immune responses triggered by the enteric pathogen can affect the joints. Shigella is classically linked to this pattern because infection with Shigella often leads to a post-infectious inflammatory arthritis, typically appearing after the diarrheal illness resolves. The mechanism involves immune cross-reactivity and inflammatory mediators that target joint tissues, sometimes with accompanying eye or urinary symptoms, and is frequently associated with HLA-B27.

Other choices describe pathogens more aligned with septic arthritis or infections not as strongly tied to post-infectious joint inflammation. Staphylococcus aureus commonly causes direct bacterial arthritis, while Streptococcus pneumoniae and Escherichia coli are not the archetypal triggers for enteropathic arthritis. Thus, Shigella stands out as the bacteria most commonly implicated in enteropathic arthropathies.