A case report of bacteremia manifesting as an overwhelming postsplenectomy infection due to Streptococcus pneumoniae post vaccination
Discussion
OPSI is characterized by severe distinct or concomitant infections causing pneumonia, meningitis, SBP, and sepsis. The clinical course progresses to coma and death within 24–48 h, due to the high incidence of shock, hypoglycemia, marked acidosis, electrolyte abnormalities, respiratory distress, and disseminated intravascular coagulation [5, 6]. Without the spleen, prompt antibody production against a new antigen is impaired and rapid bacteria proliferation causes increased infection rate of pneumococcal diseases (12–25 times greater than in the population at large) [7].
SBP that occurs in patients with liver cirrhosis has some well-known disease-specific mechanisms. Based on the clinical observations, patients with portal hypertension are prone to develop bacterial translocation that conceivably causes SBP. This translocation is supported by increased levels of lipopolysaccharide which is a surrogate parameter of gram-negative bacteremia [8], bacterial overgrowth in the small bowel [9], and decreased barrier function of the intestine in patients with liver cirrhosis [10]. Our patient had portal hypertension that increased the probability of SBP irrespective of splenectomy. Notably, previous investigations on a substantial number of patients with cirrhosis and ascitic fluid infection revealed that SBP in the patients showed high mortality, and Escherichia coli (61.3 %) and S. pneumoniae (11.3 %) were the most causative organisms. Although we hesitated to draw ascites for bacterial examination due to high risk of intraperitoneal bleeding at the puncture, it turned out that the patient had bacteremia by blood culture test performed on admission. It was found that increased creatinine 1.1 mg/dL and a positive blood culture were independent factors involved in mortality [11]. Our patient had both these factors; however, she recovered without any complications.
To our knowledge, there are no studies conducted on the occurrence of OPSI after vaccination, except one that focused on patients with hematologic disorders [1]. In our case, we considered two probabilities. First, appropriate vaccination might have decreased the severity of OPSI resulting in rapid and remarkable recovery from bacteremia caused by S. pneumoniae. The patient had no immune response-related disorder, although the vaccination was performed after splenectomy. Second, failure of the vaccination might have caused severe infectious state by S. pneumoniae. However, the latter is unlikely to occur in the current case because the patient was not under immunosuppressive state. Patients with cirrhosis or portal hypertension might need a careful follow-up after splenectomy, and a large-scale cohort study of patients with cirrhosis who have undergone splenectomy is necessary to clarify this issue.