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The rapid emergence of resistance to newly introduced antimicrobial agents suggests that resistance genes likely predated the development and use of such drugs. To explore this hypothesis, investigators studied bacterial DNA obtained from 30,000-year-old permafrost sediments in northwestern Canada.
Rigorous monitoring was performed to exclude contamination of the samples with modern DNA, and sample age was confirmed by analyses for the presence of DNA from ancient flora and megafauna (such as mammoths) and the absence of DNA from modern flora and fauna (e.g., spruce, elk).
Analysis of bacterial DNA from these samples identified genes encoding TetM, a ribosomal protection protein that confers tetracycline resistance; VanX, a component of the v…