A Case of Pneumonia and Parapneumonic Effusion Caused by Streptococcus parasanguinis

Streptococcus parasanguinis is a Viridans group bacteria that is most often discovered in the oral cavity and causes dental plaque and endocarditis in a rat model. It has low virulence but an unknown relationship to human respiratory infections. We report on a 61-year-old woman who developed hemoptysis followed by pleuritic chest pain after conscious sedation during a gastroscopic polypectomy and was diagnosed with pneumonia and parapneumonic effusion from Streptococcus parasanguinis isolated in pleural fluid. Microaspiration during the procedure was presumed to play a role in the pathogenesis.