Olecranon Osteomyelitis due to Actinomyces meyeri: Report of a Culture-Proven Case.

Actinomyces meyeri is a Gram positive, strict anaerobic bacterium, which was first described by Meyer in 1911. Primary actinomycotic osteomyelitis is rare and primarily affects the cervicofacial region, including mandible. We present an unusual case of osteomyelitis of a long bone combined with myoabscess due to A. meyeri. A 70-year-old man was admitted for pain and pus discharge of the right elbow. Twenty-five days before admission, he had hit his elbow against a table. MRI of the elbow showed a partial tear of the distal triceps tendon and myositis. He underwent open debridement and partial bone resection for the osteomyelitis of the olecranon. Biopsy showed no sulfur granules, but acute and chronic osteomyelitis. The excised tissue grew A. meyeri and Peptoniphilus asaccharolyticus. Intravenous ceftriaxone was administered and switched to oral amoxicillin. Infection of the extremities of actinomycosis often poses diagnostic difficulties, but it should not be neglected even when the characteristic pathologic findings are not present.