問題詳情

   Adding to recent research suggesting that the microbes in and on our bodies play acrucial role in human health—and that keeping the good bugs happy is as important askeeping the bad bugs out—Harvard scientists reported this week on how antibiotics affectinfants’ gut microbiomes. The major findings are sobering, if not entirely unexpected:repeated exposure to antibiotics lowers the diversity and robustness of children’s gutmicrobes and leads to an uptick in antibiotic resistance genes.   The study followed 39 Finnish infants for three years, beginning when they were twomonths old. Nineteen received no antibiotics at all; the others received between nine and 15treatments, mostly for ear infections and upper-respiratory ailments.    According to the senior coauthor Ramnik Xavier, the microbiome is dynamic during achild’s first three years, its composition still shifting and evolving, but after that, it’s basicallyset. The microbial makeup a child has at three is the one he or she will carry into adulthood.“So this is the most vulnerable period, during which messing with the microbiome could havelonger-term implications.”   In the children with repeated exposure to antibiotics, Xavier and a dozen colleaguesfound decreased numbers of some types of beneficial bacteria involved in training theimmune system at an early age. Among them, a group of microbes calledthe Clostridium cluster, which helps promote regulatory T-cells that help modulate theimmune system and stave off autoimmune disease.   Plus, Xavier adds, not only were there fewer species of microbes in theantibiotic-exposed children’s guts, but fewer strains of the species that were present: “just aless diverse microbiome, and less stable microbial communities. Having a diverse, rich,complex, microbial community is important for the immune education of the gut.”   Alongside that disruption, the researchers also saw a rise in the number of antibioticresistance genes in treated children. Some of those genes, encoded on the microbialchromosome, peaked with exposure to antibiotics and then fell back. But other resistancegenes, those encoded on more “mobile elements” outside the chromosome, did not decreasesharply at the end of the antibiotic course. Instead, they hung around for much longer—anunexpected and worrying discovery, Xavier says. “It clearly emphasizes the caution thatneeds to be followed in antibiotic prescriptions.…The spread of antibiotic resistance is aserious public-health issue.” (http://harvardmagazine.com)
48. The article is mainly about _____.
(A) the relationships between antibiotics and infants’ gut microbiomes
(B) suggestions on the use of antibiotics in treating ear infections
(C) the investigation of the natural trajectory of microbiome in kids with the use ofantibiotics
(D) the impact antibiotics have on infants’ gut microbiomes

參考答案

答案：D
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

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