Su Hao-Chang, Ying Guang-Guo, Tao Ran, Zhang Rui-Quan, Fogarty Lisa Reynolds, Kolpin Dana W
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
J Environ Monit. 2011 Nov;13(11):3229-36. doi: 10.1039/c1em10634a. Epub 2011 Oct 5.
Antibiotics are still widely applied in animal husbandry to prevent diseases and used as feed additives to promote animal growth. This could result in antibiotic resistance to bacteria and antibiotic residues in animals. In this paper, Enterobacteriaceae isolated from four integrated fish farms in Zhongshan, South China were tested for antibiotic resistance, tetracycline resistance genes, sulfonamide resistance genes, and class 1 integrons. The Kirby-Bauer disk diffusion method and polymerase chain reaction (PCR) assays were carried out to test antibiotic susceptibility and resistance genes, respectively. Relatively high antibiotic resistance frequencies were found, especially for ampicillin (80%), tetracycline (52%), and trimethoprim (50%). Out of 203 Enterobacteriaceae isolates, 98.5% were resistant to one or more antibiotics tested. Multiple antibiotic resistance (MAR) was found highest in animal manures with a MAR index of 0.56. Tetracycline resistance genes (tet(A), tet(C)) and sulfonamide resistance genes (sul2) were detected in more than 50% of the isolates. The intI1 gene was found in 170 isolates (83.7%). Both classic and non-classic class 1 integrons were found. Four genes, aadA5, aadA22, dfr2, and dfrA17, were detected. To our knowledge, this is the first report for molecular characterization of antibiotic resistance genes in Enterobacteriaceae isolated from integrated fish farms in China and the first time that gene cassette array dfrA17-aadA5 has been detected in such fish farms. Results of this study indicated that fish farms may be a reservoir of highly diverse and abundant antibiotic resistant genes and gene cassettes. Integrons may play a key role in multiple antibiotic resistances posing potential health risks to the general public and aquaculture.
抗生素仍广泛应用于畜牧业以预防疾病，并用作饲料添加剂以促进动物生长。这可能导致细菌产生抗生素耐药性以及动物体内出现抗生素残留。本文对从中国南方中山的四个综合养鱼场分离出的肠杆菌科细菌进行了抗生素耐药性、四环素耐药基因、磺胺类耐药基因和1类整合子检测。分别采用 Kirby-Bauer 纸片扩散法和聚合酶链反应（PCR）检测抗生素敏感性和耐药基因。发现相对较高的抗生素耐药频率，尤其是氨苄西林（80%）、四环素（52%）和甲氧苄啶（50%）。在203株肠杆菌科分离株中，98.5% 对一种或多种测试抗生素耐药。在动物粪便中发现多重抗生素耐药性（MAR）最高，MAR 指数为 0.56。超过50% 的分离株检测到四环素耐药基因（tet(A)、tet(C)）和磺胺类耐药基因（sul2）。在170株分离株（83.7%）中发现了intI1基因。发现了经典和非经典的1类整合子。检测到四个基因，aadA5、aadA22、dfr2和dfrA17。据我们所知，这是中国综合养鱼场分离出的肠杆菌科细菌抗生素耐药基因分子特征的首次报道，也是此类养鱼场首次检测到基因盒阵列dfrA17-aadA5。本研究结果表明，养鱼场可能是高度多样且丰富的抗生素耐药基因和基因盒的储存库。整合子可能在多重抗生素耐药性中起关键作用，对公众和水产养殖构成潜在健康风险。
