Colonization with antibiotic-resistant Streptococcus pneumoniae in children with sickle cell disease

Because of susceptibility to severe pneumococcal infection, children with sickle cell disease (SCD) routinely receive penicillin prophylaxis. Increasing rates of penicillin resistance have been reported throughout the world. Our objective was to assess the prevalence of nasopharyngeal colonization with Streptococcus pneumoniae and to assess the antimicrobial susceptibility of the organisms in children with SCD.

Nasopharyngeal cultures for S. pneumoniae were obtained from all children with SCD attending clinics in a statewide university-based network. Background colonization rates were determined in children attending day care centers in some of the same locations. All recovered S. pneumoniae organisms were tested for susceptibility to penicillin, and all resistant strains were examined for susceptibility to other antibiotics.

Overall nasopharyngeal pneumococcal colonization rates among children with SCD were 12%. Colonization was associated with age less than 2 years (p <0.001) and day care attendance for more than 20 hr/wk (p = 0.00005). More than half of these strains (62%) were resistant to penicillin, 33% having intermediate resistance (minimal inhibitory concentration 0.06 to 1 microgram/ml) and 29%, high level resistance (minimal inhibitory concentration > or = 2.0 microgram/ml). Penicillin resistance was associated with penicillin prophylaxis (p <0.01). Many of these organisms were also resistant to other classes of antibiotics.

Although penicillin prophylaxis and pneumococcal vaccine for patients with SCD have reduced overall nasopharyngeal colonization and disease caused by S. pneumoniae (p <0.001), a higher percentage of colonizing strains are now resistant both to penicillin and to other antimicrobial agents (p <0.01). Newer strategies for preventing disease and early management of suspected pneumococcal infection in these children must be developed.