Abstract
Actinomyces meyeri is a Gram-positive anaerobic forming bacterium of the genus Actinomyces, part of the oral cavity's flora, and its classification remains an unresolved issue. It is an extremely rare cause of disease, occurring in middle-aged immunocompetent patients and frequently misdiagnosed as malignancy or lung abscess. A 56-year-old man diagnosed with oesophageal squamous cell carcinoma had an endoscopically placed stent to palliate his dysphagia. Two weeks later he presented with thoracalgia and fever, interpreted as a common lung infection. Owing to lack of improvement, additional examinations were undertaken revealing mediastinum involvement. Unlike the good prognosis usually associated with this infection, the patient eventually died, reflecting the aggressive nature of his underlying condition. To our knowledge, this is the first report of mediastinitis by A. meyeri, supporting the described propensity of this agent to disseminate, particularly to the thoracic cavity, although probably in this case with an iatrogenic contribution.