Abstract：
We hypothesized that the residual concentrations of fluoroquinolones allowed in food (acceptable daily intake-ADIs) could select for ciprofloxacin resistance in our resident microbiota. We developed models of chronic Escherichia coli and Klebsiella pneumoniae infection in Galleria mellonella larvae and exposed them to ADI doses of ciprofloxacin via single dosing and daily dosing regimens. The emergence of ciprofloxacin resistance was assessed via isolation of the target bacteria in selective agar plates. Exposure to as low as one-tenth of the ADI dose of the single and daily dosing regimens of ciprofloxacin resulted in the selection of ciprofloxacin resistance in K. pneumoniae but not E. coli. This resistance was associated with cross-resistance to doxycycline and ceftriaxone. Whole genome sequencing revealed inactivating mutations in the transcription repressors, ramR and rrf2, as well as mutations in gyrA and gyrB. We found that ciprofloxacin doses 10-fold lower than those classified as acceptable for daily intake could induce resistance to ciprofloxacin in K. pneumoniae. These results suggest that it would be prudent to include the induction of antimicrobial resistance as a significant criterion for determining ADIs and the associated maximum residue limits in food.IMPORTANCEThis study found that the concentrations of ciprofloxacin/enrofloxacin allowed in food can induce de novo ciprofloxacin resistance in Klebsiella pneumoniae. This suggests that it would be prudent to reconsider the criteria used to determine \"safe\" upper concentration limits in food.
摘要：
我们假设食物中允许的氟喹诺酮类药物的残留浓度（可接受的每日摄入量-ADI）可以选择我们常驻微生物群中的环丙沙星耐药性。我们开发了海棠幼虫中慢性大肠杆菌和肺炎克雷伯菌感染的模型，并通过单次给药和每日给药方案将其暴露于ADI剂量的环丙沙星。通过在选择性琼脂平板中分离目标细菌来评估环丙沙星抗性的出现。暴露于环丙沙星单次和每日给药方案的ADI剂量的十分之一，导致肺炎克雷伯菌对环丙沙星耐药性的选择，而不是大肠杆菌。这种耐药性与多西环素和头孢曲松的交叉耐药性有关。全基因组测序显示转录阻遏物的失活突变，ramR和rrf2，以及gyrA和gyrB中的突变。我们发现，环丙沙星的剂量比每天可接受的剂量低10倍，可能会引起肺炎克雷伯菌对环丙沙星的耐药性。这些结果表明，将抗生素耐药性的诱导作为确定食品中ADI和相关的最大残留限量的重要标准是谨慎的。重要意义本研究发现，食物中允许的环丙沙星/恩诺沙星浓度可诱导肺炎克雷伯菌对环丙沙星的从头耐药。这表明，重新考虑用于确定食品中“安全”浓度上限的标准是明智的。
