Streptococcus anginosus Infections Crossing Tissue Planes

Streptococcus anginosus has long been recognized to cause invasive pyogenic infections. This holds true for thoracic infections where S anginosus has a propensity for abscess and empyema formation. Early diagnosis is important given the significant morbidity and mortality associated with thoracic S anginosus infections. Yet, distinguishing thoracic S anginosus clinically is difficult. We present three cases of thoracic S anginosus that demonstrated radiographic extension across tissue planes, including the interlobar fissure, diaphragm, and chest wall. Few infectious etiologies are known to cross tissue planes. Accordingly, we propose S anginosus be considered among the differential diagnosis of potential infectious etiologies causing radiographic extension across tissue planes.