Pyomyositis and septic hip arthritis due to bacteroides fragilis. A case report.

Bacteroides fragilis is a rare cause of pyomyositis or septic arthritis. We present the case of a 74-year-old otherwise healthy male who presented with fever and right hip pain ten days after a course of intramuscular injections. Magnetic resonance imaging (MRI) showed septic arthritis of the right hip joint and pyomyositis of the right gluteus minimus muscle. Blood cultures and pus aspirated from the muscle grew Bacteroides fragilis. The patient was treated successfully with surgical debridement and metronidazole, administered for six weeks intravenously and five weeks orally. Simultaneous pyomyositis and hip septic arthritis due to Bacteroides fragilis is rare, but should be considered possible after intramuscular injections.