School of Life Science, Sichuan University, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Key Laboratory of Bio-resources and Eco-environment, Ministry of Education, "985 Project" Science Innovative Platform for Resource and Environment Protection of Southwestern, 29 Wangjiang Road, Chengdu, Sichuan, 610064, PR China.
China Conservation and Research Center for the Giant Panda, Wolong, Sichuan 623006, PR China.
Microb Pathog. 2018 Mar;116:173-179. doi: 10.1016/j.micpath.2018.01.034. Epub 2018 Feb 20.
Escherichia coli (E. coli) is considered as a common opportunistic pathogen, which causes seriously intestinal infections to giant pandas (Ailuropoda melanoleuca) and other animals. The aim of this investigation was to characterize the antimicrobial resistance and integron gene cassettes in E. coli isolated from the faeces of giant pandas in China. A total of 89 E. coli were isolated, after diagnosis of isolates and genomes were extracted. All the isolates were screened for the presence of related drug-resistance genes and integron gene cassettes through the Polymerase Chain Reaction (PCR) and sequencing. In addition, antimicrobial resistance testing was performed according to the standard disk diffusion method (CLSI 2013). The results demonstrated that all the isolates were multi-drug resistance (MDR). High resistance proportions of the E. coli isolates were to streptomycin (93%), cefazolin (90%), amikacin (75%), tetracycline (65%), ampicillin (62%), cefotaxime and trimethoprim-sulfamethoxazole (54%, each). With respect to the various resistance genes; bla, sul1, ant (3')-Ia, tetA, qnrB, tetE, floR, aac (6')-Ib, sul2, rmtA, cmlA, rmtB and tetC were identified with the respective frequencies of 44%, 45%, 38%, 37%, 35%, 27%, 26%, 20%, 18%, 15%, 10%, 7% and 4%. None of the isolates was positive for qnrA and cfr genes. Moreover, a further investigation of integron revealed that the emergence of class 1 and 2 integrons were in 47% and 8% isolates, respectively. While class 3 integron was not screened. Six types of containing in class 1 integron specific gene cassettes (dfrA12-orfF-aadA2, dfrA17-aadA5, aadA1, aadA5, dfrA1 and dfrA7) were identified. However, only one gene cassette (dfrA1-sat2-aadA1) was detected in class 2 integron. These finding emphasize that a high level of E. coli isolates harbored antibiotics resistance and integron gene cassettes, which may bring so many potential threats to the health of giant pandas.
大肠杆菌（E. coli）被认为是一种常见的机会性病原体，可导致大熊猫（Ailuropoda melanoleuca）和其他动物严重的肠道感染。本研究旨在分析中国大熊猫粪便中分离的大肠杆菌的抗菌药物耐药性和整合子基因盒。通过诊断分离物并提取基因组后，共分离出 89 株大肠杆菌。通过聚合酶链反应（PCR）和测序，所有分离株均筛查了相关耐药基因和整合子基因盒。此外，根据标准圆盘扩散法（CLSI 2013）进行了抗菌药物耐药性测试。结果表明，所有分离株均为多重耐药（MDR）。大肠杆菌分离株对链霉素（93%）、头孢唑林（90%）、阿米卡星（75%）、四环素（65%）、氨苄西林（62%）、头孢噻肟和磺胺甲恶唑（54%，各）的耐药率较高。就各种耐药基因而言；bla、sul1、ant（3）-Ia、tetA、qnrB、tetE、floR、aac（6）-Ib、sul2、rmtA、cmlA、rmtB 和 tetC 的检出率分别为 44%、45%、38%、37%、35%、27%、26%、20%、18%、15%、10%、7%和 4%。未分离到 qnrA 和 cfr 基因。此外，对整合子的进一步研究表明，1 类和 2 类整合子的出现率分别为 47%和 8%。而 3 类整合子则未检出。在 1 类整合子中发现了 6 种包含特定基因盒的类型（dfrA12-orfF-aadA2、dfrA17-aadA5、aadA1、aadA5、dfrA1 和 dfrA7）。然而，在 2 类整合子中仅检测到一个基因盒（dfrA1-sat2-aadA1）。这些发现强调了高水平的大肠杆菌分离株携带抗生素耐药性和整合子基因盒，这可能给大熊猫的健康带来许多潜在威胁。
