农村婴幼儿肠道菌群耐药性特征及抗生素使用与食物抗生素残留对耐药性形成的影响

Diarrhea is one of major causes that affect the health and survival of infants and young children in rural areas. Feeding practice, nutritional status, disease and health seeking behavior is closely related with the occurrence of diarrhea. Antibiotic-associated diarrhea and intestinal flora antibiotic resistance problem has become the focus of attention of public health, as increasingly prominent antibiotics abuse, antibiotic residues in food. Based on our previous studies on common diseases among infants and young children in rural area and antibiotic prescribing patterns in village health clinics, the present study combining cross-sectional survey and laboratory tests will be conducted to investigate the prevalence of diarrhea in infants and young children in rural areas and their health seeking behavior by household survey. The anal swab will be collected from infants and young children to clarify the cause of diarrhea and major pathogen distribution, testing the intestinal flora antibiotic resistance. Animal-derived food species and prescriptions in village health clinics are also collected. The study aims to focus on antibiotic prescribing patterns in village health clinics and the status of antibiotic residues in animal-derived complementary food, and their association with occurrence of diarrhea and intestinal flora antibiotics resistant, combined with feeding practices, nutrition and growth development, among infants and young children in rural areas. The finding of this study will contribute to develop the guideline for diarrhea treatment and provide theoretical reference for intestinal flora antibiotics resistant control, and look for clues for further study on the causes of intestinal flora resistance.

腹泻是影响农村婴幼儿健康和生存的主要原因之一。喂养模式、营养状况、疾病及就医行为等与腹泻的发生密切相关。随着抗生素滥用、食品中抗生素残留问题的日渐突出，抗生素相关性腹泻及婴幼儿肠道菌群耐药性问题也成为公共卫生关注的热点。在既往农村婴幼儿常见病及就医行为、村级医疗机构处方特点等研究的基础上，采用现况调查与实验室检测相结合的方法，以农村婴幼儿为目标人群，调查农村婴幼儿腹泻的患病率、就医行为，同时采集粪便样本分析农村婴幼儿腹泻的原因及主要致病菌分布，检测肠道菌群的耐药性特点；收集动物性辅食样品及村卫生室处方，从基层医疗行为中抗生素的使用和动物性辅食中抗生素残留等方面入手，结合婴幼儿喂养模式、营养与生长发育状况，初步探讨农村婴幼儿肠道菌群耐药性形成的原因，为农村婴幼儿腹泻规范化治疗及控制肠道菌群耐药性产生提供理论依据，并为进一步探讨肠道菌群耐药性的成因寻找研究线索。

婴幼儿期是微生物在体内定值、逐渐趋于成人化的关键时期，其平衡性和稳定性差，感染性疾病高发，抗生素滥用及抗生素耐药问题严重。以农村婴幼儿为研究对象，采用病例（腹泻患儿）对照（健康婴幼儿）研究设计，探讨腹泻、抗生素使用、肠道菌群多样性、喂养模式、动物源性食品抗生素残留等与肠道菌群常用抗生素耐药性之间的复杂关联，将有助于明确农村婴幼儿肠道菌群耐药性特点及成因，为农村婴幼儿腹泻的预防、规范化治疗及控制肠道菌群耐药性形成提供理论依据。主要研究成果包括：（1）农村婴幼儿肠道菌群构成及多样性特点，表现为农村2岁以下婴幼儿肠道菌群结构相对简单，具有更大的不稳定性和个体特异性。（2）筛选制备肠道菌群耐药基因检测芯片，以四环素类、喹诺酮类作为动物源性辅食耐药性传递的线索，头孢类作为儿科用药导致耐药的线索，筛选制备五种肠道菌群耐药基因检测芯片。包括四环素类耐药基因型（tetM、tetQ），喹诺酮类耐药基因型（qnra、qnrs），及头孢类耐药基因型（bl2e-cfxa）。（3）腹泻及抗生素使用对肠道菌群多样性及定值抗力有明显影响，随着腹泻进入恢复期，肠道菌群的定值抗力明显改善。腹泻、抗生素使用可明显增加耐药基因型（tetM, tetQ, qnrs, cfxa）的检出率。（4）筛选出与肠道菌群多样性及耐药性相关的其他因素，包括分娩方式、喂养方式、地域、生长阶段、季节等。辅食的多样化有助于改善肠道菌群定值抗力。与出生时相比，tetM、cfxa耐药基因的检出率在6个月以内急剧上升，此后维持在一个稳定的水平；而乳类辅食的引入明显增加肠道菌群四种耐药基因型（tetM, tetQ, qnrs, cfxa）的检出率，蛋肉类辅食引入则明显增加tetQ、cfxa耐药基因型的检出率。（5）抗生素耐药成因复杂。结合婴幼儿不同的发育阶段，强调辅食多样化及安全性，特别是动物源性辅食（奶、蛋、肉）的安全性，有助于改善农村婴幼儿肠道菌群的定值抗力和稳定性，减少腹泻发生和抗生素使用，进而控制抗生素耐药性形成和传递。