Empyema caused by Streptococcus constellatus: a case reportSi Lei, Xu Yan, Zhuo Hui,Ye Yun, Luo Yingquan（Department of General Medicine, the Second Xiangya Hospital of Central South University, Changsha, 410000, China）Corresponding author: Luo Yingquan. E-mail: luoyingquan@csu.edu.cn. Department of General Medicine, Second Xiangya Hospital, Central South University, Changsha, 410000, China. Ye Yun, E-mail: