Although bacterial vaginosis is the most common and benign vaginal infection worldwide, some cases of severe acute infections have been described in the literature. We report the case of a 57-year-old French female who developed a life-threatening postoperative peritonitis after a total hysterectomy with adnexectomy in the context of the removal of leiomyosarcoma. The microbiological analysis of the peritoneal fluid identified Gardnerella vaginalis and Atobopium vaginae. The final diagnosis was a septic shock induced by an early onset peritonitis caused by Gardnerella vaginalis and Atobopium vaginae. The normal flora of the genital area could lead to a serious life threatening postoperative infection and should always be in the differential diagnosis.