Pneumococcal colonization in children with sickle cell disease [see comment].

OBJECTIVE: The goals of this prospective study were to define the Streptococcus pneumoniae colonization rate in children with sickle cell disease (SCD) at the Children's Hospital of Philadelphia and to determine the serotype and antibiotic susceptibility of all isolates. METHODS: Children with SCD followed at the hospital were sampled for colonization with S. pneumoniae by means of a throat or nasopharyngeal swab on one or two occasions. Patient information was obtained when the specimen was collected. Specimens were isolated on gentamicin-blood agar plates and modified Avery broth. Antibiotic susceptibility was determined by a commercially available test (E-test). Isolates were serotyped with the use of type-specific antisera. The relationship between the data noted above and certain clinical parameters was examined. RESULTS: A total of 490 specimens were obtained from 278 patients. Twenty-eight patients had a culture positive for S. pneumoniae, resulting in an overall colonization rate of 10%. Thirty-three percent (11/33) of all isolates were resistant to penicillin-seven intermediately resistant and four highly resistant. Twelve percent of isolates were also resistant to cefotaxime. Eight different serotypes were identified; all but one are included in the current 23-valent pneumococcal vaccine. Penicillin prophylaxis did not increase the rate of colonization with resistant strains of pneumococcus. CONCLUSION: Our results do not support a change in the current use of penicillin prophylaxis nor in the acute management of the febrile child with SCD.

Relationship between Fc receptor IIA polymorphism and infection in children with sickle cell disease.

OBJECTIVE: Despite penicillin prophylaxis and vaccination, infection with encapsulated organisms remains a leading cause of morbidity and death in children with sickle cell disease. The role of Fc receptors in the clearance of encapsulated organisms is well documented. The His(H)-Arg(R) polymorphism at amino acid 131 of the Fc gamma RIIA receptor alters binding affinity for human IgG2 and influences infection with encapsulated organisms in children without sickle cell disease. We hypothesized that the genotype for high-affinity human IgG2 binding (H/H131) is underrepresented in children with sickle cell disease who had encapsulated organism infection. DESIGN: We studied 60 black children with sickle cell disease from four participating centers who had a history of encapsulated organism infection. Genomic DNA from peripheral blood was subjected to amplification by polymerase chain reaction and to sequence analysis for identification of the Fc gamma RIIA genotype, and the genotype distribution was then compared with our data from ethnically matched control subjects. RESULTS: Contrary to our hypothesis, the H/H131 genotype was overrepresented in all individuals (p = 0.046) and in particular in the 11 individuals with a history of Haemophilus influenzae type b infection (64% H/H131, 27% H/R131, 9% R/R131; p = 0.002), in comparison with ethnically matched control subjects (14% H/H131, 60% H/R131, 26% R/R131). In the 51 individuals with a history of Streptococcus pneumoniae infection, the genotype distribution was not statistically significantly different from that of the control population. CONCLUSIONS: The H/H131 Fc gamma RIIA genotype is overrepresented in black children with sickle cell disease and a history of H. influenzae type b infection but not in those with S. pneumoniae infection.