生后抗生素暴露对早产儿肠道微生态的影响

Impact of postnatal exposure to antibiotics on intestinal microbiome in preterm infants

目的应用16S rDNA测序技术动态监测早产儿使用抗生素前后肠道微生物菌群的变化，以探讨抗生素应用对早产儿肠道微生态的影响。方法选取本院2015年9月至2016年2月期间，生后即入住新生儿科的早产儿19例，于生后1 d内，以及生后第2或3周分别收集粪便标本各1次。根据生后抗生素使用时间分为短期抗生素组（〈3 d）10例和长期抗生素组（〉7 d）9例。采用高通量测序仪Hiseq 2500对粪便样品进行测序，获得样本中细菌组成、物种丰度、系统进化、群落比较信息。采用独立样本t检验或Fisher精确概率法对数据进行统计学分析。结果（1）2组早产儿一般资料比较差异无统计学意义。（2）抗生素应用前的菌种组成以乳球菌属、肠球菌属和杆菌属为主（分别占36.41%、23.40%和14.98%）；应用后菌种组成以肠球菌属为主（16.73%），而乳球菌属与杆菌属的比例明显下降（分别为1.73%和1.25%）（P值均〈0.01）。同时，葡萄球菌属、梭菌属和双歧杆菌属比例上升。（3）应用抗生素后，短期和长期抗生素组的Shannon指数明显降低[应用前后分别为（2.34±0.84）与（1.06±0.96）和（2.64±1.04）与（0.35±0.36），P值均〈0.05]，而Chao1指数、检测物种数指数和谱系多样性指数也显现相应趋势，组内差异有统计学意义（P值均〈0.05）。（4）Beta多样性分析发现，在抗生素应用前，2组微生物群落聚集性较高；而2组组内抗生素应用后聚集性降低。（5）Anosim相似性分析发现，短期和长期抗生素组内在应用抗生素前后比较，肠道菌群构成差异均有统计学意义（R值分别为0.555和0.733，P值均=0.001）；但应用抗生素后2组间比较，差异无统计学意义（R=0.060，P=0.138）。结论抗生素的应用可明显改变早产儿肠道菌群的分布，生后短期使用抗生素即可显著改变早产儿肠道微生态的多样性。这一影响可能随抗生素使用时间延长而加重。提示临床应慎重使用抗生素，包括经验性短期使用抗生素。

ObjectiveTo assess the impact of postnatal exposure to antibiotics on intestinal microbiome in preterm infants with 16S rDNA sequencing technology.MethodsThis study was conducted on 19 preterm infants admitted to the neonatal intensive care unit （NICU） at Tongji Hospital immediately after birth from September 2015 to February 2016. Two groups were set up according to the duration of antibiotic exposure （〈3 d, n=10; 〉7 d, n=9）. Fecal samples were collected from each infant within the first day and 2 or 3 weeks after bitrth. High-throughput sequencer （Hiseq 2500） was used for sequencing, from which information on composition and abundance of species, phylogenetic evolution and bacterial community diversity was obtained. Intergroup differences was analyzed with independent samples t-test or Fisher＇s exact test.Results（1） No statistically significant difference was found in general information about the infants between the two groups. （2） The intestinal flora in preterm infants was mainly composed of Lactococcus, Enterococcus and Bacillus for both groups before antibiotic treatment （36.41%, 23.40% and 14.98%）. The proportions of Lactococcus and Bacillus were decreased significantly （1.73% and 1.25%, P〈0.01） with Enterococcus becoming the predomiant genus （16.73%） after antibiotic treatment, while the relative proportions of Staphylococcus, Clostridium and Bifidobacterium were raised. （3） The Shannon index was decreased after antibiotic exposure [（2.34±0.84） vs （1.06±0.96） in 〈3 d group, and （2.64±1.04） vs （0.35±0.36） in 〉7 d group, both P〈0.05], and the other three Alpha diversity indexes, including observed species, Chao1 and PD whole tree indexes, were also decreased within each group （all P〈0.05）. （4） Bacterial assemblages showed high beta diversity in both groups before the usage of antibiotics, but antibiotic therapy reduced the diversity. （5） Anoism analysis showed significant differences in the composition of intestinal flora within each group before and after antibiotic exposure （R=0.555 and 0.733, both P=0.001）, but no difference was found between the two groups after antibiotic exposure （R=0.060, P=0.138）.ConclusionsAntibiotic exposure, even short-term （〈3 d） administration, may significantly change the distribution of intestinal microbiota in preterm infants. Prolonged usage of antibiotics could have detrimental influence on intestinal flora. Therefore, for preterm babies, prescription of antibiotics should be cautious, even short-term empirical usage.