Serotype distribution and penicillin-binding protein genes of Streptococcus pneumoniae in children with invasive pneumococcal infection

Between August 1998 and July 2005, we studied the serotypes and mutation of penicillin-binding protein (PBP) genes of 46 strains of Streptococcus pneumoniae isolated from children with invasive pneumococcal infection in Hokkaido. The clinical diagnosis was pneumonia in 16 cases, occult bacteremia in 15, meningitis in 8, upper respiratory infection in 6, and arthritis in 1. Patients ranged in age from 2 months to 9 years old. Prevalent serotypes were 6B (39.1%), 23F (17.4%) 6A (8.7%), and 19F (8.7%). The serotype coverage rate by the 7-valent pneumococcal vaccine was greater than 70% in children. Mutation of 3 genes (Penicillin-binding S. pneumoniae, PRSP) was detected in 18 isolates, mutation of 10 genes (pbp1a and pbp2x, or pbp2x and pbp2b) in 2, and of pbp2x alone in 15. PRSP was found in serotypes 6A, 6B, and 23F, and the rate of PRSP in 6A, 6B, and 23F was 75.0%, 62.5%, and 55.6%, respectively.