A 48-year-old female with a past medical history of diabetes and hypertension presented with a three-day history of stabbing chest pain radiating to the neck. Prior to the onset of symptoms, she had struck her chest on the steering wheel of a bumper car at an amusement park. She also endorsed getting a dental procedure about ten days prior to presentation.
Physical examination revealed tachycardia, poor dentition, sternal tenderness and scratch marks on her anterior chest. Laboratory data was significant for a mild leukocytosis and an elevated D-dimer. Given persistent tachycardia, chest pain and an elevated D-dimer, a chest CT angiogram (CTA) was done to rule out a pulmonary embolism (PE). Chest CTA was negative for a PE, but showed a 6.6 x1.5 cm fluid collection which, in the context of her bumper car injury, was diagnosed as a retrosternal hematoma.
On hospital day 2, she became febrile to 102.5 °F. Blood cultures grew gram positive cocci which later speciated to methicillin-sensitive Staphylococcus aureus (MSSA). She underwent a CT soft tissue neck with contrast which showed mediastinitis, anterior chest wall cellulitis, retropharyngeal cellulitis with airway narrowing and multiple dental caries. She underwent incision and drainage, and operative fluid cultures also grew MSSA.
Discussion:
Acute mediastinitis is a severe infection of the thoracic cavity which must be promptly recognized and treated to avoid sepsis and to prevent airway compromise. It most commonly occurs as a complication of cardiac surgery. However, it can also occur as a complication of a primary odontogenic or pharyngeal infection descending down cervical fascial planes into the mediastinum, an entity termed descending necrotizing mediastinitis. Rare cases of acute mediastinitis have been reported following blunt trauma to the chest without esophageal perforation.
Mediastinitis of odontogenic origin is typically polymicrobial, with mixed aerobic and anaerobic oral flora. Common aerobic organisms include alpha-hemolytic streptococcus and Staphyloccus aureus, while common anaerobic organisms include Peptosteptoccus and Bacteroides fragilis. The case above describes a monomicrobial infection with MSSA which is typically unusual for mediastinitis of odontogenic origin. A potential source of mediastinitis in our patient could be her skin, especially given the presence of multiple scratches on her chest, bumper car injury leading to blunt chest wall trauma prior to symptom onset, MSSA bacteremia and an anterior chest wall cellulitis seen on CT soft tissue head and neck. Blunt chest wall trauma leading to MSSA bacteremia is a rare cause of mediastinitis in the non-cardiac surgery population.
Conclusions:
This case highlights the importance of careful history taking and avoidance of premature closure, particularly when the differential includes life-threatening conditions like acute mediastinitis.