The overwhelming post splenectomy infection (OPSI) in splenectomised patients is a rare but severe infection mostly caused by encapsulated bacteria. We analyse the case of a 65-year-old female patient who was presented with clinical and laboratory findings indicating gastroenteritis. Two years years before admission, the patient underwent a splenectomy for a two stage splenic rupture following resuscitation for pulmonary embolism. Immunisation of the patient was complete and timely. As a result of the unspecific clinical presentation, there was a delay in administration of antibiotics. However, administration of antibiotics induced a fulminant shock. The patient died 4 hours after attending the hospital due to a pneumococcal sepsis. The discussion highlights epidemiological and pathophysiological aspects and potential prevention strategies in the international context. Vaccination failed in our patient as the isolated pneumococcal strain (serogroup: 12F) is usually covered by the 23-valent pneumococcal polysaccharide vaccination (Pneumovax(®)). The case reported here indicates that there may be a potential benefit of prophylactic antibiotic treatment within the first 3 years after splenectomy for patients above the age of 65 years. Awareness of OPSI (prevention strategies, symptoms and treatment) among patients and their treating physicians is crucial for the improvement of prognosis. We partly address these issues in a standard operating procedure for the assessment of splenectomised patients in our departments of emergency medicine.