Beall Bernard, Chochua Sopio, Metcalf Ben, Lin Wuling, Tran Theresa, Li Zhongya, Li Yuan, Bentz Meghan L, Sheth Mili, Osis Gunars, McGee Lesley
Contractor to Division of Bacterial Diseases, Centers for Disease Control and Prevention, Eagle Global Scientific, LLC, Atlanta, Georgia, USA.
Respiratory Diseases Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
J Infect Dis. 2025 Apr 15;231(4):871-882. doi: 10.1093/infdis/jiae453.
The Centers for Disease Control and Prevention's Active Bacterial Core surveillance (ABCs) identified increased serotype 4 invasive pneumococcal disease (IPD), particularly among adults experiencing homelessness (AEH).
We quantified increased proportions of IPD cases in AEH during 2016-2022. Employing genomic-based characterization of IPD isolates, we identified serotype-switch variants. Recombinational analyses were used to identify the genetic donor and recipient strain that generated a serotype 4 progeny strain. We performed phylogenetic analyses of the serotype 4 progeny and of the serotype 12F genetic recipient to determine genetic distances.
We identified a cluster of 30 highly related (0-21 nucleotide differences) IPD isolates recovered during 2022-2023, corresponding to a serotype 4 capsular-switch variant. This strain arose through a multifragment recombination event between serotype 4/ST10172 and serotype 12F/ST220 parental strains. Twenty-five of the 30 cases occurred in Oregon. Of 29 cases with known residence status, 16 occurred in AEH. Variant emergence coincided with a 2.6-fold increase (57 to 148) of cases caused by the serotype 4/ST10172 donor lineage in 2022 compared to 2019 and its first appearance in Oregon. Most serotypes showed sequential increases of AEH IPD/all IPD ratios during 2016-2022 (eg, for all serotypes combined, 247/2198, 11.2% during 2022 compared to 405/5317, 7.6% for 2018-2019, P < .001). Serotypes 4 and 12F each caused more IPD than any other serotype in AEH during 2020-2022 (207 combined case isolates accounting for 38% of all IPD in AEH).
Expansion and increased transmission of serotypes 4 and 12F among adults potentially led to recent genesis of an impactful hybrid serotype-switch variant.
美国疾病控制与预防中心的主动细菌核心监测（ABCs）发现4型侵袭性肺炎球菌病（IPD）有所增加，尤其是在无家可归成年人（AEH）中。
我们对2016年至2022年期间AEH中IPD病例增加的比例进行了量化。利用IPD分离株的基因组特征，我们鉴定了血清型转换变体。重组分析用于鉴定产生4型后代菌株的基因供体和受体菌株。我们对4型后代菌株和12F型基因受体菌株进行了系统发育分析，以确定遗传距离。
我们鉴定出一组在2022年至2023年期间分离出的30株高度相关（0至21个核苷酸差异）的IPD分离株，对应于一种4型荚膜转换变体。该菌株是通过4型/ST10172和12F型/ST220亲本菌株之间的多片段重组事件产生的。30例病例中有25例发生在俄勒冈州。在29例已知居住状况的病例中，16例发生在AEH中。变体的出现与2022年4型/ST10172供体谱系引起的病例数相比2019年增加了2.6倍（从57例增至148例）以及其在俄勒冈州首次出现相吻合。在2016年至2022年期间，大多数血清型的AEH IPD/所有IPD比率呈逐步上升趋势（例如，所有血清型合并计算，2022年为247/2198，占11.2%，而2018年至2019年为405/5317，占7.6%，P <.001）。在2020年至2022年期间，4型和12F型血清型在AEH中引起的IPD均多于任何其他血清型（207例合并病例分离株占AEH中所有IPD的38%）。
4型和12F型血清型在成年人中的传播扩大和增加，可能导致了一种有影响力的杂交血清型转换变体的近期产生。
