A 64-year-old woman was diagnosed with hereditary spherocytosis 30 years ago and underwent splenectomy. She presented to the hospital with lower abdominal pain and was diagnosed with sigmoid colon cancer(cT3N3M1[LYM], H1, Stage Ⅳ)for which sigmoidectomy was performed. On the 7th postoperative day, a fever of 40℃ and an inflammatory reaction were observed. She developed a consciousness disorder the next day, and her condition rapidly deteriorated along with the development of septic shock and disseminated intravascular coagulation(DIC). With the aid of a ventilator, immediate treatment for DIC was started, but reversion of septic shock and DIC was not possible, and the patient died of multiple organ dysfunction on the 17th postoperative day. Computed tomography and urinalysis performed during the course of treatment showed no infected lesion, but Citrobacter spp. was detected thrice in venous blood culture. Hence, the patient was diagnosed as a case of Citrobacter overwhelming post splenectomy infection(OPSI). To our knowledge, this is the first report of Citrobacter spp. infection following an abrupt course of OPSI.
