Streptococcus pneumoniae Serotype 12F-CC4846 and Invasive Pneumococcal Disease after Introduction of 13-Valent Pneumococcal Conjugate Vaccine, Japan, 2015–2017

Abstract

To prevent invasive pneumococcal disease (IPD), pneumococcal conjugate vaccines (PCVs) have been implemented in many countries; however, many cases of IPD still occur and can be attributable to nonvaccine serotypes of Streptococcus pneumoniae . In Japan, the number of IPD cases attributable to serotype 12F increased from 4.4% in 2015 to 24.6% in 2017 after 13-valent PCV was introduced. To clarify the associated genetic characteristics, we conducted whole-genome sequencing of 75 serotype 12F isolates. We identified 2 sequence types (STs) among the isolates: ST4846, which was the major type, and ST6945. Bayesian analysis suggested that these types diverged in »1942. Among serotype 12F-ST4846, we identified a major cluster, PC-JP12F, whose time of most recent common ancestor was estimated to be »2012. A phylogeographic analysis demonstrated that PC-JP12F isolates spread from the Kanto region, the most populated region in Japan, to other local regions.

Frequent Transmission of Streptococcus pneumoniae Serotype 35B and 35D, Clonal Complex 558 Lineage, across Continents and the Formation of Multiple Clades in Japan

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Whole-Genome Analysis-Based Phylogeographic Investigation of Streptococcus pneumoniae Serotype 19A Sequence Type 320 Isolates in Japan

“…We performed PBP typing ( 3 , 25 , 26 ), resistance gene identification, and pilus detection as described previously ( 14 , 24 , 27 ). In brief, after read trimming, we assembled the obtained sequence reads and extracted the pbp1a , pbp2b , and pbp2x regions from the contigs using BLAST+ version 2.6.0 ( 28 ).…”