Which encapsulated bacterium is commonly used as an example of risk for individuals without a spleen?

Which encapsulated bacterium is commonly used as an example of risk for individuals without a spleen?

• A. Haemophilus influenzae
• B. Neisseria meningitidis
• C. Streptococcus pneumoniae
• D. Staphylococcus aureus

Answer: (C)

The spleen plays a key role in defending against encapsulated bacteria by filtering blood and providing opsonizing antibodies that coat polysaccharide capsules, promoting phagocytosis by macrophages. When the spleen is absent or nonfunctional, this opsonization and clearance are impaired, leaving individuals more vulnerable to sepsis from encapsulated organisms. Streptococcus pneumoniae is the classic example because it has a polysaccharide capsule that helps it resist phagocytosis unless opsonized. In people without a spleen, pneumococcal bacteremia can rapidly become severe, making it the organism most commonly cited in discussions of infection risk for asplenic patients. While other encapsulated bacteria like Haemophilus influenzae and Neisseria meningitidis also pose risks in this context, pneumococcus is the best-known and most frequently emphasized example.

The spleen plays a key role in defending against encapsulated bacteria by filtering blood and providing opsonizing antibodies that coat polysaccharide capsules, promoting phagocytosis by macrophages. When the spleen is absent or nonfunctional, this opsonization and clearance are impaired, leaving individuals more vulnerable to sepsis from encapsulated organisms.

Streptococcus pneumoniae is the classic example because it has a polysaccharide capsule that helps it resist phagocytosis unless opsonized. In people without a spleen, pneumococcal bacteremia can rapidly become severe, making it the organism most commonly cited in discussions of infection risk for asplenic patients. While other encapsulated bacteria like Haemophilus influenzae and Neisseria meningitidis also pose risks in this context, pneumococcus is the best-known and most frequently emphasized example.