Background: Acute mediastinitis is the inflammation of the connective tissue and fat surrounding the mediastinal structures. It is a high-mortality entity and its most frequent causes include sternotomy infections from cardiovascular surgery, esophageal perforation and extension of head and neck infections. Isolated cases of acute mediastinitis from hematogenous spread are described in the literature. Case presentation: 58 year-old man, with history of gouty arthritis managed with steroids, diagnosed with acute mediastinitis by S. aureus, secondary to septic arthritis of the ankle, managed with drainage of mediastinal collections by thoracoscopy and antibiotic therapy, with satisfactory evolution. Conclusions: In patients with acute mediastinitis, hematogenous dissemination should be considered when the etiologies most frequently associated with the entity are ruled out. Early surgical treatment derived from a multidisciplinary diagnostic approach improves the prognosis of these patients.