A 52-year-old woman with Crohn’s disease presented with septic arthrtis of the knee. This condition coincided with a symptomatic flare of her Crohn’s disease due to an ileal inflammatory stenosis, manifested as a phlegmonous mass palpable in the right lower quadrant and a small bowel obstruction. Results of synovial fluid cultures showed the presence of Gram-negative bacillus, Klebsiella pneumoniae and the CT scan images were highly suggestive of abdominal abscess within Crohn’s disease. The patient’s condition improved after following an antibiotic treatment and after the initiation of Anti-TNF-alpha agent Adalimumab, with no further exacerbation. Septic arthritis in Crohn’s disease should be considered to have a communicating source of sepsis consisting of an abdominal abscess or fistula.

Abbreviations: Anti-TNF-alpha agent = anti tumor necrosis factor alpha agent, 5-ASA = 5-aminosalicylic acid