A 30-year-old white male presented to your office with low back pain and stiffness. His pain is worse in the morning and is improved with activity. He has also been having bloody diarrhea for the past few days. On examination, he has painful erythematous nodules over his shins. Pain and stiffness is present in his lower back. Plain radiographs show sacroiliac joint inflammation. Stool cultures are negative. Laboratory studies show anemia and thrombocytosis. P-ANCA is positive in high titers. Which of the following is the most likely cause of his symptoms?
A. Reactive arthritis from diarrhea
B. lnflammatory bowel disease
C. Infection with T ropheryma whippelii
D. Gluten-sensitive enteropathy
E. Infection with Giardia Iamblia