Rodrigues Marinelle, Sabaeifard Parastoo, Yildiz Muhammed Sadik, Coughlin Laura, Ahmed Sara, Behrendt Cassie, Wang Xiaoyu, Monogue Marguerite, Kim Jiwoong, Gan Shuheng, Zhan Xiaowei, Filkins Laura, Williams Noelle S, Hooper Lora V, Koh Andrew Y, Toprak Erdal
bioRxiv. 2023 Jan 11:2023.01.11.523617. doi: 10.1101/2023.01.11.523617.
systems have provided great insight into the mechanisms of antibiotic resistance. Yet, approaches cannot reflect the full complexity of what transpires within a host. As the mammalian gut is host to trillions of resident bacteria and thus a potential breeding ground for antibiotic resistance, we sought to better understand how gut bacteria respond to antibiotic treatment . Here, we colonized germ-free mice with a genetically barcoded antibiotic pan-susceptible clinical isolate and then administered the antibiotic cefepime via programmable subcutaneous pumps which allowed for closer emulation of human parenteral antibiotic pharmacokinetics/dynamics. After seven days of antibiotics, we were unable to culture from feces. We were, however, able to recover barcoded from harvested gastrointestinal (GI) tissue, despite high GI tract and plasma cefepime concentrations. Strikingly, these isolates were not resistant to cefepime but had acquired mutations â€" most notably in the gene, which encodes an enzyme required for the initiation of the synthesis of the polysaccharide capsule and lipopolysaccharide O antigen - that increased their ability to invade and survive within intestinal cells, including cultured human colonocytes. Further, these mutants exhibited a persister phenotype when exposed to cefepime, allowing for greater survival to pulses of cefepime treatment when compared to the wildtype strain. Our findings highlight a mechanism by which bacteria in the gastrointestinal tract can adapt to antibiotic treatment by increasing their ability to persist during antibiotic treatment and invade intestinal epithelial cells where antibiotic concentrations are substantially reduced.
各种系统已经为深入了解抗生素耐药机制提供了很大帮助。然而，这些方法无法反映宿主内所发生情况的全部复杂性。由于哺乳动物肠道内寄生着数万亿细菌，因此是抗生素耐药性的一个潜在滋生地，我们试图更好地了解肠道细菌如何对抗生素治疗作出反应。在此，我们用一种带有基因条形码的对所有抗生素敏感的临床分离株对无菌小鼠进行定殖，然后通过可编程皮下泵给予抗生素头孢吡肟，这样能更接近地模拟人类肠胃外抗生素的药代动力学/药效学。使用抗生素七天后，我们无法从粪便中培养出（相关细菌）。然而，尽管胃肠道和血浆中头孢吡肟浓度很高，我们仍能够从收获的胃肠道（GI）组织中回收带有条形码的（细菌）。引人注目的是，这些分离株对头孢吡肟并不耐药，但已经发生了突变——最显著的是在（某个）基因中，该基因编码一种启动多糖荚膜和脂多糖O抗原合成所需的酶——这增强了它们在肠道细胞（包括培养的人结肠细胞）内侵袭和存活的能力。此外，当暴露于头孢吡肟时，这些（细菌）突变体表现出持留菌表型，与野生型菌株相比，在头孢吡肟脉冲治疗下能有更高的存活率。我们的研究结果突出了一种机制，通过这种机制，胃肠道中的细菌可以通过提高其在抗生素治疗期间的存活能力以及侵入抗生素浓度大幅降低的肠道上皮细胞的能力来适应抗生素治疗。
