摘要

抗生素在治疗细菌性疾病中的高度使用是动物蛋白质大量生产的主要问题之一。智利的鲑鱼养殖是上述声明的一个明显例子，过去10年中使用了超过5,500吨抗生素。这对生产层面和环境都产生了很大的影响;然而，与之相关的作品仍然很少。为了证明大量使用抗生素对鱼肠道微生物群的影响，我们选择了四个鲑鱼养殖场，其中大西洋鲑鱼（Salmo salar）的鱼类数量相似，为4,500至6,000吨。所有这些农场都使用高剂量的抗生素治疗。因此，选择15只健康鱼并实施安乐死，以便从肠道微生物群中分离出对抗生素土霉素和氟苯尼考具有抗性的细菌。共分离到47株对氟苯尼考耐药的细菌分离株和44株对土霉素有抗药性，其中氟苯尼考的最低抑菌浓度（MIC）超过2048μg/ mL，土霉素的最低抑菌浓度为1024μg/ mL。此外，还测试了另外六种不同的抗生素以证明多重抗性现象。在这方面，发现了6种91的分离株，其中8种受试抗生素的抗性值升高，包括氟苯尼考和土霉素。这些细菌被称为“超级抗性”细菌。这种表型抗性在基因型水平上得到验证，因为大多数分离株显示出对氟苯尼考和土霉素的抗生素抗性基因（ARG）。具体而言，77％的抗生素抗性细菌显示至少一种对氟苯尼考具有抗性的基因，89％显示出至少一种对土霉素具有抗性的基因。在本研究中，证明了抗生素氟苯尼考和土霉素的高度使用，因此，在海水阶段选择了Salmo salar物种的养殖鱼的肠道微生物群中的多重耐药细菌。此外，这些细菌的表型抗性可与抗生素抗性基因的存在相关联。

The high use of antibiotics for the treatment of bacterial diseases is one of the main problems in the mass production of animal protein. Salmon farming in Chile is a clear example of the above statement, where more than 5,500 tonnes of antibiotics have been used over the last 10 years. This has caused a great impact both at the production level and on the environment; however, there are still few works in relation to it. In order to demonstrate the impact of the high use of antibiotics on fish gut microbiota, we have selected four salmon farms presenting a similar amount of fish of the Atlantic salmon species (Salmo salar), ranging from 4,500 to 6,000 tonnes. All of these farms used treatments with high doses of antibiotics. Thus, 15 healthy fish were selected and euthanised in order to isolate the bacteria resistant to the antibiotics oxytetracycline and florfenicol from the gut microbiota. In total, 47 bacterial isolates resistant to florfenicol and 44 resistant to oxytetracycline were isolated, among which isolates with Minimum Inhibitory Concentrations (MIC) exceeding 2048 μg/mL for florfenicol and 1024 μg/mL for oxytetracycline were found. In addition, another six different antibiotics were tested in order to demonstrate the multiresistance phenomenon. In this regard, six isolates of 91 showed elevated resistance values for the eight tested antibiotics, including florfenicol and oxytetracycline, were found. These bacteria were called "super-resistant" bacteria. This phenotypic resistance was verified at a genotypic level since most isolates showed antibiotic resistance genes (ARGs) to florfenicol and oxytetracycline. Specifically, 77% of antibiotic resistant bacteria showed at least one gene resistant to florfenicol and 89% showed at least one gene resistant to oxytetracycline. In the present study, it was demonstrated that the high use of the antibiotics florfenicol and oxytetracycline has, as a consequence, the selection of multiresistant bacteria in the gut microbiota of farmed fish of the Salmo salar species at the seawater stage. Also, the phenotypic resistance of these bacteria can be correlated with the presence of antibiotic resistance genes.

https://www.ncbi.nlm.nih.gov/pubmed/30204782