摘要

       由于抗生素在畜禽粪便中的广泛应用，多种抗生素耐药基因（ARGs）在畜禽粪便中的流行率较高。然而，ARGs在细菌之间，特别是在不同种类的多重耐药菌（MARB）之间的分布和传播特性还没有得到很好的研究。通过应用高通量测序方法，我们的研究发现了一个巨大的畜禽粪便库。大肠埃希菌属、粘虫属、不动杆菌属、变形杆菌属、Ignatzschineria属、产碱菌属、普罗维登氏菌属和肠球菌属为优势种，其组成为40.6%-85.7%。从鸡粪分离物中筛选出33株MARB，用于研究其耐药性的分子特征。共检测到61个ARGs和18个流动基因元件。我们发现在33个MARB分离株中广泛分布着47个ARGs。每个分离物携带27-36个基因，负责对临床或兽医环境中常用的八类抗生素的耐药性。除链霉素和万古霉素外，其余6类抗生素的ARGs均存在于33株MARB中，患病率为80%-100%。33株MARB中广泛分布着12株MGEs，其中intI1、IS26、ISaba1和ISEcp1同时存在于100%的分离株中。此外，在编码不同抗生素类耐药性的MARB分离株中检测到9个整合子和ISCR1基因盒。这是第一份报告，揭示了在鸡粪中不同种类的单个MARB分离物中多个ARGs、不同MGEs和ARG盒的普遍存在。结果显示，ARGs通过畜禽粪便传播给人类的风险远高于我们的预期。

       Diverse antibiotic-resistance genes (ARGs) are frequently reported to have high prevalence in veterinary manure samples due to extensive use of antibiotics in farm animals. However, the characteristics of the distribution and transmission of ARGs among bacteria, especially among different species of multiple antibiotic-resistant bacteria (MARB), have not been well explored. By applying high-throughput sequencing methods, our study uncovered a vast MARB reservoir in livestock manure. The genera Escherichia, Myroides, Acinetobacter, Proteus, Ignatzschineria, Alcaligenes, Providencia and Enterococcus were the predominant cultivable MARB, with compositions of 40.6%-85.7%. From chicken manure isolates, 33 MARB were selected for investigation of the molecular characteristics of antibiotic resistance. A total of 61 ARGs and 18 mobile genetic elements (MGEs) were investigated. We found that 47 ARGs were widely distributed among the 33 MARB isolates. Each isolate carried 27-36 genes responsible for resistance to eight classes of antibiotics frequently used in clinic or veterinary settings. ARGs to the six classes of antibiotics other than streptogramins and vancomycin were present in all 33 MARB isolates with a prevalence of 80%-100%. A total of 12 MGEs were widely distributed among the 33 MARB, with intI1, IS26, ISaba1, and ISEcp1 simultaneously present in 100% of isolates. In addition, 9 gene cassettes within integrons and ISCR1 were detected among MARB isolates encoding resistance to different antibiotic classes. This is the first report revealing the general co-presence of multiple ARGs, various MGEs and ARG cassettes in different species of individual MARB isolates in chicken manure. The results highlight a much higher risk of ARGs spreading through livestock manure to humans than we expected.

       https://www.sciencedirect.com/science/article/pii/S0269749117301963?via%3Dihub