Which organism is classically associated with sepsis in asplenic or functionally asplenic patients with sickle cell disease?

• A. Streptococcus pneumoniae
• B. Staphylococcus aureus
• C. Escherichia coli
• D. Pseudomonas aeruginosa

Answer: (A)

Loss of splenic function, as occurs with autosplenectomy in sickle cell disease or after splenectomy, removes a key line of defense against encapsulated bacteria. The spleen filters and helps clear organisms with polysaccharide capsules from the bloodstream, so when it’s not working, these pathogens can cause rapid, overwhelming sepsis. The organism most classically linked to this risk is Streptococcus pneumoniae, the quintessential encapsulated bacterium in asplenic or functionally asplenic patients. This is why pneumococcal vaccination and prophylactic measures are especially important in sickle cell disease. While other bacteria can cause sepsis in various settings, the strong association here is with pneumococcus due to the lack of splenic immune function.