Instituto de Microbiologia, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
APDP-Diabetes Portugal, Lisbon, Portugal.
Microbiol Spectr. 2022 Jun 29;10(3):e0108222. doi: 10.1128/spectrum.01082-22. Epub 2022 May 23.
The prevalence and lineages of Streptococcus agalactiae (group B streptococci [GBS]) colonizing pregnant women are well studied, but less is known about colonization of nonpregnant adults. We characterized GBS colonization in adults as a potential reservoir for infections and tested for the presence of clones with a potentially higher invasive disease potential. We evaluated GBS gastrointestinal, genitourinary, and oral colonization among 336 nonpregnant adults in the community. We characterized the isolates by serotyping, multilocus sequence typing, profiling of surface protein genes and pili, and antimicrobial susceptibility and compared them with contemporary invasive isolates. The colonization rate ( = 107, 32%) among nonpregnant adults was like that of pregnant women. Colonization increased with age (~25% in the 18 to 29 and 30 to 44 years old groups and >42% in the ≥60 years old group), potentially explaining the higher incidence of disease with older age. Participants who were colonized at multiple sites (73%) were frequently carrying indistinguishable strains (93%), consistent with the existence of a single reservoir of colonization and transfer of GBS between sites within the same individual. The most frequent lineages found were serotype Ib/CC1 ( = 27), serotype V/CC1 ( = 19), serotype Ia/CC23 ( = 13), serotype III/ST17 ( = 13), and serotype Ib/CC10 ( = 11). Comparison with contemporary isolates causing invasive infections in Portugal did not reveal any lineage associated with either asymptomatic carriage or invasive disease. Asymptomatic colonization of nonpregnant adults is significant and could act as a reservoir for invasive disease, but in contrast to infant disease, we found no GBS lineages with an enhanced potential for causing invasive disease in adults. The increasing incidence of Streptococcus agalactiae (group B streptococci [GBS]) infections in adults and the inability of antimicrobial prophylaxis peripartum to control late-onset infections in infants motivate the study of the asymptomatic carrier state in nonpregnant adults. We found an overall carriage rate like that of pregnant women, increasing with age, potentially contributing to the higher incidence of GBS infections with age. Colonization of diabetic participants was not higher despite the higher number of infections in this group. Comparison between contemporary genetic lineages causing infections and found in asymptomatic carriers did not identify particularly virulent lineages. This means that any prophylactic approaches targeting colonization by particular lineages are expected to have a limited impact on GBS disease in adults.
研究表明，孕妇中定植的无乳链球菌（B 群链球菌）的流行率和谱系已经得到了很好的研究，但对于非孕妇成人的定植情况了解较少。我们对成人的 B 群链球菌定植情况进行了特征描述，将其视为感染的潜在储库，并检测了具有更高侵袭性疾病潜力的克隆体的存在。我们评估了 336 名社区中非孕妇成人的胃肠道、泌尿生殖道和口腔定植情况。我们通过血清分型、多位点序列分型、表面蛋白基因和菌毛特征分析以及抗菌药物敏感性对分离株进行了特征描述，并与同期侵袭性分离株进行了比较。非孕妇成人的定植率（ = 107，32%）与孕妇相似。随着年龄的增长，定植率逐渐增加（18-29 岁和 30-44 岁年龄组约为 25%，≥60 岁年龄组>42%），这可能解释了年龄较大与疾病发生率较高之间的关系。在多个部位定植的参与者（73%）经常携带无法区分的菌株（93%），这与定植的单一储库以及个体内部的 GBS 从一个部位转移到另一个部位的情况相符。最常见的谱系是血清型 Ib/CC1（ = 27）、血清型 V/CC1（ = 19）、血清型 Ia/CC23（ = 13）、血清型 III/ST17（ = 13）和血清型 Ib/CC10（ = 11）。与葡萄牙同期引起侵袭性感染的分离株进行比较，未发现与无症状定植或侵袭性疾病相关的任何谱系。非孕妇成人的无症状定植现象显著，可能成为侵袭性疾病的储库，但与婴儿疾病不同，我们未发现任何 GBS 谱系具有导致成人侵袭性疾病的增强潜力。无乳链球菌（B 群链球菌）感染在成人中的发病率不断增加，且围产期抗菌药物预防无法控制婴儿晚期感染，这促使我们研究非孕妇成人的无症状携带状态。我们发现，总体定植率与孕妇相似，随年龄增长而增加，这可能导致年龄较大的 GBS 感染发病率增加。尽管该组感染人数较多，但糖尿病患者的定植率并没有更高。与无症状携带者中发现的引起感染的当代遗传谱系进行比较，并未发现特别毒力的谱系。这意味着，针对特定谱系定植的任何预防性方法预计对成人 GBS 疾病的影响有限。
