Daily penicillin prophylaxis in a 6-week-old with homozygous HbS reduces the risk of infection with which organism?

• A. Streptococcus pneumoniae
• B. Neisseria meningitidis
• C. Haemophilus influenzae
• D. Escherichia coli

Answer: (A)

In sickle cell disease, the spleen often becomes functionally absent early in life, so the body is less able to clear encapsulated bacteria from the bloodstream. This makes infants especially susceptible to sepsis from encapsulated organisms, with Streptococcus pneumoniae being the leading threat. Daily penicillin prophylaxis in a young infant with sickle cell disease reduces carriage and bloodstream infection by pneumococcus, significantly lowering the risk of pneumococcal sepsis and meningitis. Vaccination strategies also address Hib and meningococcus, but the specific benefit of this penicillin regimen is the reduction in pneumococcal infections. Thus, the regimen targets Streptococcus pneumoniae infection most effectively.