Effects of a Four-Week High-Dosage Zinc Oxide Supplemented Diet on Commensal Escherichia coli of Weaned Pigs
Effects of a Four-Week High-Dosage Zinc Oxide Supplemented Diet on Commensal Escherichia coli of Weaned Pigs
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DOI：
10.3389/fmicb.2019.02734
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发表时间：
2019-11-28
影响因子：
5.2
通讯作者：
Wieler, Lothar H.
中科院分区：
文献类型：
--
作者：
Johanns, Vanessa C.;Ghazisaeedi, Fereshteh;Wieler, Lothar H.
减少猪场断奶后腹泻相关经济损失的策略包括高水平的饲粮氧化锌补充。然而，在养猪生产部门过量使用氧化锌被发现与这些动物体内多药耐药细菌的积累有关，通过污染的粪便造成环境负担。在这里，我们报告了在对照饲养试验中从16头断奶仔猪中随机选择的肠道大肠杆菌的锌耐受性，这些大肠杆菌包括不同的抗生素耐药表型和采样点：从“高锌饲猪”（高锌组，[HZG]: n = 99）和相应的“对照组”（[CG]）中分离出的179株菌株。n = 80)通过测定最低抑菌浓度（mic）对锌耐受性、抗菌剂和杀菌剂敏感性进行了研究。此外，利用内部基于blast的管道进行了抗生素耐药基因（ARGs）以及杀菌剂和重金属耐受基因的全基因组筛选（WGSc）。总体而言，猪大肠杆菌分离株表现出三种不同的ZnCl2 mic: 128 μ g/ml (HZG, 2%； CG, 6%), 256 μ g/ml （HZG, 64%； CG, 91%）和512 μ g/ml ZnCl2 (HZG, 34%， CG, 3%)，单峰分布很可能反映了不同遗传谱系锌耐受性的自然差异。然而，富锌补充饲料的选择性影响似乎是合理的，因为线性混合回归模型显示，“高”的ZnCl2 mic与代表HZG的分离株之间存在统计学显著关联，“低”的ZnCl2 mic与代表CG的分离株之间存在统计学显著关联（p = 0.005）。没有一种氯化锌MICs与特定的抗生素、重金属或杀菌剂耐受/耐药表型相关。表达512 μ g/ml MIC的菌株要么对氨基糖苷类、四环素和磺胺甲氧苄唑-甲氧苄啶具有耐药性的ARGs呈阳性，要么根本没有ARGs。此外，WGSc显示锌稳态和解毒基因普遍存在，包括zitB， zntA和pit。总之，我们提供的证据表明，猪饲料中富含锌的补充选择了更具锌耐受性的大肠杆菌，包括含有ARGs和生物杀灭剂和重金属耐受基因的分离株，考虑到目前工业化猪肉生产系统中使用的物质和抗生素，这是一种假定的选择优势。
Strategies to reduce economic losses associated with post-weaning diarrhea in pig farming include high-level dietary zinc oxide supplementation. However, excessive usage of zinc oxide in the pig production sector was found to be associated with accumulation of multidrug resistant bacteria in these animals, presenting an environmental burden through contaminated manure. Here we report on zinc tolerance among a random selection of intestinal Escherichia coli comprising of different antibiotic resistance phenotypes and sampling sites isolated during a controlled feeding trial from 16 weaned piglets: In total, 179 isolates from "pigs fed with high zinc concentrations" (high zinc group, [HZG]: n = 99) and a corresponding "control group" ([CG]: n = 80) were investigated with regard to zinc tolerance, antimicrobial- and biocide susceptibilities by determining minimum inhibitory concentrations (MICs). In addition, in silico whole genome screening (WGSc) for antibiotic resistance genes (ARGs) as well as biocide- and heavy metal tolerance genes was performed using an in-house BLAST-based pipeline. Overall, porcine E. coli isolates showed three different ZnCl2 MICs: 128 mu g/ml (HZG, 2%; CG, 6%), 256 mu g/ml (HZG, 64%; CG, 91%) and 512 mu g/ml ZnCl2 (HZG, 34%, CG, 3%), a unimodal distribution most likely reflecting natural differences in zinc tolerance associated with different genetic lineages. However, a selective impact of the zinc-rich supplemented diet seems to be reasonable, since the linear mixed regression model revealed a statistically significant association between "higher" ZnCl2 MICs and isolates representing the HZG as well as "lower ZnCl2 MICs" with isolates of the CG (p = 0.005). None of the zinc chloride MICs was associated with a particular antibiotic-, heavy metal- or biocide- tolerance/resistance phenotype. Isolates expressing the 512 mu g/ml MIC were either positive for ARGs conferring resistance to aminoglycosides, tetracycline and sulfamethoxazole-trimethoprim, or harbored no ARGs at all. Moreover, WGSc revealed a ubiquitous presence of zinc homeostasis and - detoxification genes, including zitB, zntA, and pit. In conclusion, we provide evidence that zinc-rich supplementation of pig feed selects for more zinc tolerant E. coli, including isolates harboring ARGs and biocide- and heavy metal tolerance genes - a putative selective advantage considering substances and antibiotics currently used in industrial pork production systems.