This case is significant to the practice of emergency medicine because it represents the development of an uncommon and potentially fatal mediastinal infection from a commonly encountered and appropriately treated community respiratory pathogen. Most published reports on mediastinitis are those that are status-post cardiothoracic surgery. In our report, we discuss a case of a healthy, young individual who developed this morbid entity from extension of a simple respiratory infection where Group C Streptococcus has been isolated as the causative organism, which to our knowledge has not been previously reported. Further, this report outlines how a community acquired pneumonia progressed to a life threatening illness despite proper initial treatment per local and national guidelines.