Delport Tiffany C, Harcourt Robert G, Beaumont Linda J, Webster Koa N, Power Michelle L
1 Department of Biological Sciences, Faculty of Science, Macquarie University, Sydney, NSW 2109, Australia.
J Wildl Dis. 2015 Jul;51(3):555-63. doi: 10.7589/2014-08-200. Epub 2015 Apr 28.
Greater interaction between humans and wildlife populations poses significant risks of anthropogenic impact to natural ecosystems, especially in the marine environment. Understanding the spread of microorganisms at the marine interface is therefore important if we are to mitigate adverse effects on marine wildlife. We investigated the establishment of Escherichia coli in the endangered Australian sea lion (Neophoca cinerea) by comparing fecal isolation from wild and captive sea lion populations. Fecal samples were collected from wild colonies March 2009-September 2010 and from captive individuals March 2011-May 2013. Using molecular screening, we assigned a phylotype to E. coli isolates and determined the presence of integrons, mobile genetic elements that capture gene cassettes conferring resistance to antimicrobial agents common in fecal coliforms. Group B2 was the most abundant phylotype in all E. coli isolates (n = 37), with groups A, B1, and D also identified. Integrons were not observed in E. coli (n = 21) isolated from wild sea lions, but were identified in E. coli from captive animals (n = 16), from which class I integrases were detected in eight isolates. Sequencing of gene cassette arrays identified genes conferring resistance to streptomycin-spectinomycin (aadA1) and trimethoprim (dfrA17, dfrB4). Class II integrases were not detected in the E. coli isolates. The frequent detection in captive sea lions of E. coli with resistance genes commonly identified in human clinical cases suggests that conditions experienced in captivity may contribute to establishment. Identification of antibiotic resistance in the microbiota of Australian sea lions provides crucial information for disease management. Our data will inform conservation management strategies and provide a mechanism to monitor microorganism dissemination to sensitive pinniped populations.
人类与野生动物种群之间日益频繁的互动给自然生态系统带来了重大的人为影响风险，尤其是在海洋环境中。因此，如果我们要减轻对海洋野生动物的不利影响，了解微生物在海洋界面的传播就很重要。我们通过比较野生和圈养海狮种群的粪便分离情况，研究了大肠杆菌在濒危的澳大利亚海狮（Neophoca cinerea）体内的定植情况。粪便样本于2009年3月至2010年9月从野生群体中采集，于2011年3月至2013年5月从圈养个体中采集。通过分子筛选，我们为大肠杆菌分离株确定了一个系统型，并确定了整合子的存在，整合子是一种可捕获基因盒的移动遗传元件，这些基因盒赋予了对粪便大肠菌群中常见抗菌剂的抗性。B2组是所有大肠杆菌分离株（n = 37）中最丰富的系统型，同时也鉴定出了A、B1和D组。在从野生海狮分离的大肠杆菌（n = 21）中未观察到整合子，但在圈养动物的大肠杆菌（n = 16）中鉴定到了整合子，其中在8个分离株中检测到了I类整合酶。基因盒阵列测序确定了赋予对链霉素-壮观霉素（aadA1）和甲氧苄啶（dfrA17、dfrB4）抗性的基因。在大肠杆菌分离株中未检测到II类整合酶。在圈养海狮中频繁检测到带有在人类临床病例中常见抗性基因的大肠杆菌，这表明圈养环境可能有助于其定植。在澳大利亚海狮微生物群中鉴定出抗生素抗性为疾病管理提供了关键信息。我们的数据将为保护管理策略提供参考，并提供一种监测微生物向敏感鳍足类种群传播的机制。
