Spread of Meropenem-Resistant Streptococcus pneumoniae Serotype 15A-ST63 Clone in Japan, 2012–2014

• Main Authors: Satoshi Nakano, Takao Fujisawa, Yutaka Ito, Bin Chang, Yasufumi Matsumura, Masaki Yamamoto, Miki Nagao, Shigeru Suga, Makoto Ohnishi, Satoshi Ichiyama
• Format: Article
• Language: English
• Published: Centers for Disease Control and Prevention 2018-02-01
• Series: Emerging Infectious Diseases
• Subjects: Streptococcus pneumoniae; meropenem resistance; antimicrobial resistance; serotype 15A; ST63; PCV7
• Online Access: https://wwwnc.cdc.gov/eid/article/24/2/17-1268_article
• ISSN: 1080-6040; 1080-6059

After the introduction of pneumococcal conjugate vaccines, the incidence of pneumococcal infections due to meropenem-resistant serotype 15A-ST63 strains increased in Japan. By using whole-genome sequencing and comparing sequences with those of clones from the United Kingdom, the United States, and Canada, we clarified the traits of the serotype 15A-ST63 clone. Our analysis revealed that the meropenem-resistant serotype 15A-ST63 strains from Japan originated from meropenem-susceptible strains from Japan. Recombination site prediction analysis showed that the meropenem-resistant strain-specific recombination regions included the pbp1a and pbp2b regions. A detailed analysis of the composition of these genes indicated that resistance seems to be caused by pbp1a recombination. The pbp1a gene in meropenem-resistant isolates was identical to that in multidrug (including meropenem)–resistant serotype 19A-ST320 pneumococci, which have spread in the United States. The global spread of pneumococci of this lineage is noteworthy because serotype 15A is not included in the currently used 13-valent pneumococcal conjugate vaccine.