Primary meningococcal arthritis of sacroiliac joint: a rare case report.

Infection of the sacroiliac joint is a rare entity. Clinical signs and symptoms are usually nonspecific and result in delayed diagnosis. We report a rare case of primary meningococcal arthritis of right sacroiliac joint in an 11-year-old male child. Synovial fluid aspirated from the joint space showed Gram-negative diplococci which were confirmed as Neisseria meningitidis by culture and necessary biochemical tests followed by serogrouping by using polyvalent antisera. He was treated successfully with antibiotics.