基于出生队列研究生命早期抗生素-益生菌暴露对婴幼儿肠道菌群耐药性传递及其他健康结局的复杂关联

Antibiotics exposure and microbiota composition in the early stages of life have a far-reaching impact on subsequent health outcomes. As the most common treatment options for infants and young children diseases, antibiotics abuse is serious problem. Antibiotic residues in the food chain further increase the chances of infants and young children been exposed to antibiotics. Antibiotics interfere with the homeostasis of infant intestinal microorganisms, and greatly increase the risk of antibiotic resistance formation and spread in the gut flora. As potential antibiotic resistance gene reservoir, probiotics, which are widely used, play a role in fueling the spread of antibiotic resistance in intestinal flora. However, the evidence from well-designed population studies were limited about complex association between antibiotic-probiotic use and the formation and transmission of antibiotics resistance in infants and young children. Based on birth cohort design, the present study will explore in-depth the complicated association between the variety of exposure in the early stages of life, with focus on type, dosage and initial time of antibiotics-probiotics using, and the composition of intestinal microbiota, inflammatory response, intestinal bacterial antibiotic resistance and other health outcomes, to investigate the potential mechanism of the formation of intestinal flora antibiotic resistance, by detecting the composition of intestinal bacterial community and bacterial antibiotics resistance genes in infants and young children dynamically. The study also provide a theoretical basis for the rational use of antibiotics and reasonable assessment of the health effects of probiotics consumption in infants and young children.

生命早期抗生素使用与菌群构成对以后的健康结局存在深远影响。抗生素作为婴幼儿最常见的治疗选择，滥用问题突出。而食物链中的抗生素残留，进一步增加了婴幼儿暴露于抗生素的机会。抗生素干扰婴幼儿肠道微生物的稳态，极大的增加肠道菌群抗生素耐药性形成和传递的可能性。被广泛应用的益生菌作为潜在的抗生素耐药基因库，对肠道菌群抗生素耐药的传播，起到推波助澜的作用。但抗生素-益生菌使用与婴幼儿肠道菌群耐药性的形成与传递之间的复杂关联缺乏设计良好的人群研究证据。本研究采用出生队列研究设计，动态检测婴幼儿肠道菌群构成及菌群耐药基因，分析生命早期抗生素-益生菌使用的时间、种类、剂量、以及其他环境暴露等，对婴幼儿肠道菌群构成、免疫应激、肠道菌群耐药性传递及其他健康结局的复杂关联，探讨肠道菌群耐药性传递的潜在机制；同时为婴幼儿抗生素的合理使用以及益生菌对婴幼儿健康效应的合理评估提供理论依据。

生命早期（产前-产时-婴幼儿期）的抗生素/益生菌暴露，干扰婴幼儿肠道微生物的定植及稳定性，极大增加抗生素耐药基因水平及垂直传递的可能性，对此后生命周期的健康结局产生深远影响。本研究通过建立母婴队列，获取母亲孕期-产时-新生儿期-婴幼儿期抗生素及益生菌暴露的特点，同时采集不同时期粪便样本进行微生物组学分析，探索真实暴露场景下，婴幼儿肠道微生物群如何塑造并逐步成人化的自然转变过程，以生命早期抗生素暴露-益生菌使用-肠道菌群稳定性-的复杂关联为研究切入点，阐明肠道菌群抗生素耐药性形成、传递的潜在机制及其对生命早期健康结局的影响。主要研究发现：（1）婴幼儿肠道菌群的耐药基因存在从外环境中水平传递而来的可能性。婴幼儿肠道菌群中绿弯菌门和酸杆菌门（土壤中的常见菌属）的相对丰度与常见兽用抗生素耐药基因检出率显著相关。月龄增长、夏秋季、奶粉类辅食添加，是影响兽用抗生素耐药基因从外环境水平传递到婴幼儿肠道菌群的关键因素。（2）母婴共享菌群存在地域化差异，且受到多种环境因素的影响。双歧杆菌和埃希氏菌/志贺氏菌是最常见的母婴共享菌，提示它们在新生儿定植和母婴垂直传播中的重要性。除双歧杆菌和拟杆菌外，很大比例的新生儿微生物群在母体微生物群中无法鉴定出，婴儿肠道微生物群的来源和功能需要进一步阐明。（3）产前（不足5%）、产时（约16%）均有不同程度的抗生素暴露。出生后6个月内约1/10的婴儿使用过抗生素，约1/5的婴儿使用过益生菌。研究发现产前、出生后6月龄内的抗生素暴露对婴幼儿肠道菌群多样性影响不明显，但产时抗生素预防不仅影响子代出生后6月龄内的肠道菌群beta多样性、菌群组成，也影响抗生素耐药性的母婴垂直传递，增加了新生儿肠道菌群中Eggerthellaceae等与各种儿童疾病相关的菌科丰度，进而可能增加婴儿的患病风险。出生后使用益生菌则明显改善婴儿肠道菌群的beta多样性。