Department of Microbiology, Tokyo Medical University, Tokyo, Japan.
Department of Bacteriology 1, National Institute of Infectious Diseases, Tokyo, Japan.
Epidemiol Infect. 2024 Oct 4;152:e114. doi: 10.1017/S0950268824001031.
serotype 35B, a non-vaccine type, is a major contributor to the increase in pneumococcal infection post-vaccination. We aimed to understand the mechanism of its spread by characterizing 35B. The serotype, type 1 pilus (T1P) positivity, and antimicrobial susceptibility of 319 isolates in 2018-2022 were analysed and compared with those of isolates in 2014-2017 to find the changes. 35B accounted for 40 (12.5%) isolates. T1P positivity was notably higher in 35B (87.5%) than in the other serotypes. To confirm the role of T1P, an adhesion factor, we compared adherence to A549 cells between -positive 35B isolates and their -deficient mutants, showing contribution of T1P to adherence. Penicillin-non-susceptible rate of 35B was 87.5%, and meropenem-resistant 35B rate was 35.0%, which increased from 14.5% of 2014-2017 ( = 0.009). Multilocus sequence typing was performed in 35B strains. Prevalence of clonal complex 558, harbouring and exhibiting multidrug non-susceptibility, suggested the advantages of 35B in attachment and survival in the host. The emergence of ST156 isolates, -positive and non-susceptible to β-lactams, has raised concern about expansion in Japan. The increase of serotype 35B in pneumococcal diseases might have occurred due to its predominant colonizing ability after the elimination of the vaccine-serotypes.
血清型 35B 为非疫苗型，是疫苗接种后肺炎球菌感染增加的主要原因。我们旨在通过对 35B 进行特征分析，了解其传播机制。分析了 2018-2022 年 319 株分离株的血清型、1 型菌毛（T1P）阳性率和抗菌药物敏感性，并与 2014-2017 年分离株进行比较，以发现变化。35B 占 40 株（12.5%）分离株。35B 的 T1P 阳性率明显高于其他血清型（87.5%）。为了确认 T1P（一种粘附因子）的作用，我们比较了 T1P 阳性和 T1P 缺陷型 35B 分离株对 A549 细胞的粘附能力，表明 T1P 有助于粘附。35B 的青霉素不敏感率为 87.5%，美罗培南耐药率为 35.0%，比 2014-2017 年的 14.5%有所增加（=0.009）。对 35B 菌株进行了多位点序列分型。携带 并表现出多药耐药性的 558 克隆复合体的流行率表明 35B 在附着和宿主生存方面具有优势。ST156 分离株的出现，T1P 阳性且对β-内酰胺类药物不敏感，引起了人们对日本扩张的关注。肺炎球菌疾病中血清型 35B 的增加可能是由于疫苗型消灭后其主要定植能力所致。
