Development of the oral micro biome during childhood: an ecological succession associated with dental health status. Oral microbiota during infancy

Information on how the oral microbiome develops during early childhood and how external factors influence this process is scarce. In the current study, we used high-throughput sequencing to characterise bacterial composition and diversity in saliva samples collected at 3, 6, 12, 24 months and 7 years of age in 90 longitudinally followed children, for whom clinical, dietary and health data were collected. Bacterial diversity and richness increased steadily from birth throughout childhood. Bacterial composition patterns changed through time, starting with “early colonizers” associated with the initial breastfeeding period, including Streptococcus and Veillonella. Other bacterial genera such as Neisseria and Actinomyces settled after one or two years of age. Caries development at 9 years of age was associated with diverging microbial composition through time. Streptococcus cristatus appeared to be associated with increased risk of developing tooth decay and its role as an etiological factor and as potential biomarker of the disease should be further studied. Infants born by C-section had initially skewed bacterial content compared to vaginally delivered infants, but this was recovered with age. However, shorter breastfeeding habits and antibiotic treatment during the first 2 years of age were both associated with a different bacterial composition at later age. Taken together, the data are consistent with oral microbiota development being an ecological succession. Thus, an altered colonization pattern during the first year of life may have long-term consequences for oral microbiome development, whose potential impact on the child's oral and systemic health should be further studied.

目前关于儿童早期口腔微生物组（oral microbiome）的发育规律，以及外部因素对该过程的影响的相关研究仍较为匮乏。本研究采用高通量测序（high-throughput sequencing）技术，对90名接受纵向追踪的儿童的唾液样本进行细菌组成与多样性分析：这些儿童分别在3月龄、6月龄、12月龄、24月龄及7岁时采集唾液样本，同时收集了其临床、饮食与健康相关数据。研究结果显示，儿童口腔细菌的多样性与丰富度自出生起呈稳步上升趋势；细菌组成模式随时间推移发生动态变化：初始阶段以与母乳喂养初期相关的早期定植菌为主，涵盖链球菌属（Streptococcus）与韦荣球菌属（Veillonella）；奈瑟菌属（Neisseria）、放线菌属（Actinomyces）等其他细菌菌属则在儿童1至2岁时逐渐定植。9岁时的龋病发病情况与儿童时期随时间变化的微生物组成差异存在关联，其中脊链球菌（Streptococcus cristatus）似乎与龋病发病风险升高密切相关，其作为该疾病的致病因子与潜在生物标志物的作用有待进一步研究。与阴道分娩婴儿相比，经剖宫产（cesarean section）分娩的婴儿初始细菌组成存在偏差，但该差异会随年龄增长逐渐恢复。然而，母乳喂养时长不足以及2岁前接受抗生素治疗，均与儿童后期口腔细菌组成的异质性存在关联。综上，本研究数据表明口腔微生物组的发育过程属于典型的生态演替过程。因此，生命第一年的定植模式异常可能会对口腔微生物组的发育产生长期影响，其对儿童口腔及全身健康的潜在作用有待进一步深入探究。