Asplenic patients are at risk for rapidly progressive septicemia and death. Such patients should be vaccinated against pneumococci, H. influenzae type b, meningococci, and influenza virus, and if fever develops, they should receive empirical antimicrobial therapy immediately. This is the topic of the latest Clinical Practice review.
Mortality among patients with postsplenectomy sepsis can be as high as 50%. Most commonly caused by Streptococcus pneumoniae, this infection often has a sudden onset and a fulminant course.
•What factors influence the risk of postsplenectomy sepsis?
The risk of postsplenectomy sepsis varies according to several factors, including the indication for splenectomy, the patient’s age at the time of the surgery, and the interval since plenectomy. With respect to indication, the risk is lowest among otherwise healthy persons who undergo splenectomy because of trauma, intermediate among patients with hereditary spherocytosis or immune thrombocytopenic purpura, and highest among surgically asplenic patients with (beta)-thalassemia, sickle cell anemia, or portal hypertension. With respect to age, the risk of sepsis is highest among infants with surgical or congenital asplenia. Children younger than 5 years at the time of splenectomy have a higher risk than older children or adults, but this finding may in part reflect the increased risk associated with the underlying conditions that warranted splenectomy (e.g., thalassemia major and sickle cell anemia). With respect to the interval since splenectomy, the risks of sepsis and associated death are highest in the first year after splenectomy, at least among young children, but remain elevated for more than 10 years and probably for life.
• What pathogen most commonly causes sepsis in patients who have undergone splenectomy?
The pathogen that most commonly causes sepsis in patients who have undergone splenectomy, as well as in children with sickle cell disease, is S. pneumoniae (pneumococcus). Another encapsulated bacteria, Haemophilus influenzae type b (Hib), which primarily affects children younger than 5 years of age, is now rare because of universal use of the Hib conjugate vaccine in the United States. Although Neisseria meningitidis, Escherichia coli, and Staphylococcus aureus each accounts for a small proportion of bloodstream isolates from asplenic persons, whether asplenia is actually a risk factor for infection with these pathogens has not been established.
Morning Report Questions
Q: What vaccines are recommended for patients who have undergone a splenectomy?
A: Several vaccines are available for some of the pathogens that cause postsplenectomy sepsis, specifically S. pneumoniae, Hib, and N. meningitidis. For prevention of pneumococcal infection, administration of PCV13 followed 8 weeks later by PPSV23 is recommended. The risk of invasive infection with Hib among adults and older children is very low. Therefore, it is reasonable to limit vaccination of adults or older children with the Hib vaccine to those who were not previously vaccinated. Quadrivalent meningococcal conjugate vaccine (MenACWY) has replaced quadrivalent meningococcal polysaccharide vaccine for patients without a spleen; a two-dose primary series is indicated for such patients. Annual vaccination against influenza virus is recommended because influenza infection confers a predisposition to bacterial pneumonia and sepsis caused by S. pneumoniae and S. aureus.
Q: How should fever in an asplenic patient be handled?
A: If fever develops in an asplenic patient, immediate administration of an antimicrobial agent is indicated, because fever can be the initial manifestation of a fulminant infection and prompt administration of an antimicrobial agent may prevent the development of clinical sepsis. Ceftriaxone administered intravenously or intramuscularly with or without vancomycin is a reasonable empirical choice. Ceftriaxone is active against most S. pneumoniae strains as well as H. influenzae, N. meningitidis, and many community-acquired gram-negative bacilli, including capnocytophaga.