The infant gut microbiota has a high abundance of antibiotic resistance genes (ARGs) compared to adults, even in the absence of antibiotic exposure. Here we study potential sources of infant gut ARGs by performing metagenomic sequencing of breast milk, as well as infant and maternal gut microbiomes. We find that fecal ARG and mobile genetic element (MGE) profiles of infants are more similar to those of their own mothers than to those of unrelated mothers. MGEs in mothers' breast milk are also shared with their own infants. Termination of breastfeeding and intrapartum antibiotic prophylaxis of mothers, which have the potential to affect microbial community composition, are associated with higher abundances of specific ARGs, the composition of which is largely shaped by bacterial phylogeny in the infant gut. Our results suggest that infants inherit the legacy of past antibiotic consumption of their mothers via transmission of genes, but microbiota composition still strongly impacts the overall resistance load.

中文翻译：

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母体肠道和母乳中的微生物群会影响婴幼儿肠道抗生素抵抗力和移动遗传成分。

与成人相比，婴儿肠道菌群具有丰富的抗生素抗性基因（ARG），即使没有抗生素暴露也是如此。在这里，我们通过对母乳以及婴儿和孕妇肠道微生物组进行宏基因组测序来研究婴儿肠道ARGs的潜在来源。我们发现婴儿的粪便ARG和移动遗传元件（MGE）谱与自己母亲的相似，而不是与无亲戚的母亲相似。母亲母乳中的MGE也与自己的婴儿共享。有可能影响微生物群落组成的母亲的终止母乳喂养和产前预防抗生素，与特定ARGs的丰度较高有关，其组成很大程度上由婴儿肠道细菌的系统发育决定。