National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
Sci Total Environ. 2021 Jun 1;771:144828. doi: 10.1016/j.scitotenv.2020.144828. Epub 2021 Jan 27.
Overuse of antibiotics in animal husbandry has led to an increase of antibiotic resistance microorganisms as well as antibiotic-resistance genes (ARGs). Duck farming in China is practiced on a large and diverse scale and the overuse of antibiotics in this field is gaining attention recently. We evaluated the diversity of ARGs from five duck farms using a functional metagenomic approach and constructed five libraries. A total of seventy-six resistant determinants were identified, of which sixty-one were gene variants or novel genes. The novel genes contained five β-lactamase-encoding genes designated as bla, bla, bla, bla and bla, respectively, and two genes conferring resistance to fosfomycin designated as fosA-like1 and fosA-like2. Three of the five β-lactamase-encoding genes were further identified as extended-spectrum β-lactamases (ESBL) that can hydrolyze both penicillins and cephalosporins. Besides, two of the five β-lactamase-encoding genes were associated with mobile genetic elements, indicating a high potential for transfer of the genes to other bacterial hosts. The two novel fosA-like genes were able to increase the MICs of the test Escherichia coli strain from 2 μg/mL to as high as 256 μg/mL(up to 128-fold increase). Our study provides a reference for ARGs prevalence in duck farm wastes and implies that they are an important resistome reservoir, especially for novel ARGs with high spread potential.
畜牧业中抗生素的过度使用导致了抗生素耐药微生物以及抗生素耐药基因（ARGs）的增加。中国的养鸭业规模庞大且多样化，该领域抗生素的过度使用最近引起了关注。我们使用功能宏基因组学方法评估了来自五个养鸭场的 ARGs 的多样性，并构建了五个文库。共鉴定出 76 个耐药决定因素，其中 61 个是基因变异或新基因。新基因包含五个分别命名为 bla、bla、bla、bla 和 bla 的β-内酰胺酶编码基因，以及两个赋予对磷霉素抗性的基因 fosA-like1 和 fosA-like2。这五个β-内酰胺酶编码基因中的三个被进一步鉴定为能够水解青霉素和头孢菌素的超广谱β-内酰胺酶（ESBL）。此外，这五个β-内酰胺酶编码基因中的两个与移动遗传元件有关，表明这些基因向其他细菌宿主转移的潜力很高。这两个新的 fosA-like 基因能够将测试大肠杆菌菌株的 MIC 从 2μg/mL 提高到 256μg/mL（高达 128 倍）。我们的研究为鸭场废物中 ARGs 的流行情况提供了参考，并表明它们是一个重要的抗性基因库，特别是对于具有高传播潜力的新型 ARGs。
