Hiroshi Sakata1, Yoshitake Sato2, Yoshikiyo Toyonaga3, Hideaki Hanaki4. 1. Department of Pediatrics, Asahikawa Kosei Hospital, Asahikawa, Hokkaido, Japan. 2. Department of Pediatrics, Subaru Health Insurance Society Ota Memorial Hospital, Ota, Gunma, Japan. 3. Department of Pediatrics, Sekishinkai Sayama Hospital, Sayama, Saitama, Japan. 4. Kitasato Institute, Kitasato University Research Center for Anti-infectious Drugs, Tokyo, Japan.
Abstract
BACKGROUND: This study examined the trends for the serotypes of S. pneumoniae that have caused infections before (2010) and after (2012) the introduction of PCV-7 in Japan. METHODS: We examined 458 strains of Streptococcus pneumoniae obtained from 22 pediatric institutions throughout Japan from January to June 2010 (immediately after the introduction of the seven-valent pneumococcal conjugate vaccine [PCV-7]), and 370 strains obtained from 19 institutions from January to June 2012 (after PCV-7 became widely used). The samples were collected from children aged 0-14 years with conditions such as respiratory tract infections (upper airway inflammation, bronchitis, and pneumonia), meningitis, and sepsis. RESULTS: The most frequent serotype in the 2010 strains was 19F (17.3%), followed by 6B (16.8%), and 23F (15.1%). The most frequent serotype in the 2012 strains was 6C (10.0%), followed by 19F (9.7%), 15A (8.9%) and 15B (8.9%), indicating a significant change in the distribution. The serotypes contained in PCV-7 were detected in 280 strains (61.1%) in 2010 and in 81 strains (21.9%) in 2012 (P < 0.01). The serotypes contained in PCV-13 were detected in 356 strains (77.7%) in 2010 and in 146 strains (39.5%) in 2012 (P < 0.01). A total of 129 subjects who had not been vaccinated with PCV-7 and 127 subjects who had been vaccinated with PCV-7 at least once, were compared with regard to the 2012 strains. The serotypes contained in PCV-7 were found in 21 strains (16.5%) in those who had been vaccinated and in 37 strains (28.7%) in those who had not been vaccinated (P < 0.05). CONCLUSIONS: The increased use of PCV-7 led to decreases in the serotypes contained in PCV-13 and increases in the serotypes not contained in PCV-13, suggesting serotype replacement.
BACKGROUND: This study examined the trends for the serotypes of S. pneumoniae that have caused infections before (2010) and after (2012) the introduction of PCV-7 in Japan. METHODS: We examined 458 strains of Streptococcus pneumoniae obtained from 22 pediatric institutions throughout Japan from January to June 2010 (immediately after the introduction of the seven-valent pneumococcal conjugate vaccine [PCV-7]), and 370 strains obtained from 19 institutions from January to June 2012 (after PCV-7 became widely used). The samples were collected from children aged 0-14 years with conditions such as respiratory tract infections (upper airway inflammation, bronchitis, and pneumonia), meningitis, and sepsis. RESULTS: The most frequent serotype in the 2010 strains was 19F (17.3%), followed by 6B (16.8%), and 23F (15.1%). The most frequent serotype in the 2012 strains was 6C (10.0%), followed by 19F (9.7%), 15A (8.9%) and 15B (8.9%), indicating a significant change in the distribution. The serotypes contained in PCV-7 were detected in 280 strains (61.1%) in 2010 and in 81 strains (21.9%) in 2012 (P < 0.01). The serotypes contained in PCV-13 were detected in 356 strains (77.7%) in 2010 and in 146 strains (39.5%) in 2012 (P < 0.01). A total of 129 subjects who had not been vaccinated with PCV-7 and 127 subjects who had been vaccinated with PCV-7 at least once, were compared with regard to the 2012 strains. The serotypes contained in PCV-7 were found in 21 strains (16.5%) in those who had been vaccinated and in 37 strains (28.7%) in those who had not been vaccinated (P < 0.05). CONCLUSIONS: The increased use of PCV-7 led to decreases in the serotypes contained in PCV-13 and increases in the serotypes not contained in PCV-13, suggesting serotype replacement.