Department of Obstetrics and Gynaecology, University of Cambridge, Cambridge, United Kingdom.
Department of Obstetrics and Gynaecology, University of Cambridge, Cambridge, United Kingdom.
Am J Obstet Gynecol. 2023 May;228(5S):S1305-S1312. doi: 10.1016/j.ajog.2022.07.051. Epub 2023 Mar 23.
Streptococcus agalactiae (group B Streptococcus) colonizes the genital tract of approximately 20% of pregnant women. In the absence of intervention, approximately 1% of infants born to colonized mothers exhibit a clinical infection. This has led to implementation of screening and intervention in the form of intrapartum antibiotic prophylaxis in many countries, including the United States. However, screening has not been introduced in a substantial minority of other countries because of the absence of supportive level 1 evidence, the very large number needed to treat to prevent 1 case, and concerns about antimicrobial resistance. Optimal screening would involve rapid turnaround (to facilitate intrapartum testing) and report antibiotic sensitivity, but no such method exists. There is significant scope for a personalized medicine approach, targeting intrapartum antibiotic prophylaxis to cases at greatest risk, but the pathogen and host factors determining the risk of invasive disease are incompletely understood. Epidemiologic data have indicated the potential of prelabor invasion of the uterus by group B Streptococcus, and metagenomic analysis revealed the presence of group B Streptococcus in the placenta in approximately 5% of pregnant women at term before onset of labor and membrane rupture. However, the determinants and consequences of prelabor invasion of the uterus by group B Streptococcus remain to be established. The vast majority (98%) of invasive neonatal disease is caused by 6 serotypes, and hexavalent vaccines against these serotypes have completed phase 2 trials. However, an obstacle to phase 3 studies is conducting an adequately powered trial to demonstrate clinical effectiveness given that early-onset disease affects approximately 1 in 1000 births in the absence of vaccination.
无乳链球菌（B 群链球菌）定植于约 20%孕妇的生殖道。未经干预的情况下，定植孕妇所分娩的婴儿中约有 1%会出现临床感染。这导致包括美国在内的许多国家实施了筛查和干预措施，即产时抗生素预防。然而，由于缺乏支持 1 级证据、需要治疗的人数非常多才能预防 1 例感染，以及对耐药性的担忧，在少数其他国家并未引入筛查。最佳筛查方法涉及快速周转（以促进产时检测）和报告抗生素敏感性，但目前尚无此类方法。个性化医学方法具有很大的应用空间，将产时抗生素预防措施针对风险最大的病例，但决定侵袭性疾病风险的病原体和宿主因素尚未完全了解。流行病学数据表明，B 群链球菌在分娩前可能已经侵入子宫，宏基因组分析显示，在无临产和胎膜破裂的足月孕妇中，约有 5%的胎盘存在 B 群链球菌。然而，B 群链球菌在分娩前侵入子宫的决定因素和后果仍有待确定。绝大多数（98%）侵袭性新生儿疾病由 6 种血清型引起，针对这些血清型的六价疫苗已完成 2 期临床试验。然而，由于在没有疫苗的情况下，早发型疾病影响约每 1000 例出生中就有 1 例，因此进行足够有力的试验以证明临床有效性是 3 期研究的一个障碍。
