Abstract
Arcanobacterium haemolyticum causes pharyngeal and skin lesions but rarely causes severe systemic infections. An 80-year-old woman with diabetes mellitus was admitted for surgery of a left femoral neck fracture and right first toe ulcer. On day 19, chest radiography revealed a massive left pleural effusion.Pleural fluid culture grew Staphylococcus aureus and A. haemolyticum. The fluid was drained via a chest tube, and the patient was treated with cefazolin and clindamycin. Only four cases of pyothorax caused by A. haemolyticum have been reported, and no previous cases of A. haemolyticum pyothorax with bacterial co-infections have been reported.