Duration of penicillin prophylaxis in sickle cell anemia: issues and controversies.

Functional asplenia occurs in 94% of patients with homozygous sickle cell anemia by 5 years of age and may result in fatal septicemia due to encapsulated microorganisms such as Streptococcus pneumoniae. Penicillin prophylaxis in these patients significantly reduces the risk of septicemia; however, continuation of prophylaxis beyond 5 years of age is controversial, since the risk of developing septicemia is reduced after this age and prolonged prophylaxis may lead to emergence of penicillin resistance. Although reports of penicillin-resistant pneumococci in patients receiving penicillin prophylaxis are conflicting, the prevalence of these organisms in the general population in North America increased from 5% in 1989 to more than 35% in 1997. Discontinuation of prophylaxis after age 5 years may be recommended because of lack of benefit, difficulty maintaining compliance, reduced risk of developing pneumococcal bacteremia after that age, and increase in prevalence of penicillin-resistant pneumococci worldwide.