Lemierre-like syndrome and severe descending mediastinitis in an Infant with retropharyngeal abscess due to methicillin susceptible Staphylococcus aureus.

An 11-month-old girl presented with fever, respiratory distress and septic shock. She had no neck stiffness, swelling, difficulty swallowing, or drooling. An echocardiogram that was done to evaluate cardiac function showed compression of the innominate vein. Subsequent cross-sectional imaging revealed retropharyngeal abscess (RPA) with extensive descending mediastinitis and abscesses as well as septic thrombophlebitis involving the left internal jugular vein, subclavian vein, and innominate vein, consistent with Lemierre-like syndrome. Blood cultures grew methicillin-susceptible Staphylococcus aureus (MSSA). The patient had surgical drainage of the RPA, followed by mediastinal catheter placement. However, she eventually required a cardiopulmonary bypass for a complete mediastinal exploration and drainage with thymectomy, left lung decortication, and an allograft patch repair of superior vena cava (SVC) erosion under deep hypothermic circulatory arrest. Despite resolution of infection with drainage and antibiotics, the clinical course was complicated by bilateral diaphragmatic paralysis, and the need for a tracheostomy and ventilatory support. The case highlights the potential for life-threatening complications of RPA due to S. aureus in infants. RPA and mediastinitis may develop in infants without the usual clinical findings of deep neck infection. Early recognition, prompt imaging, and aggressive multidisciplinary management are crucial for improving outcomes.