Genetic basis, transferability and co-selection of macrolide resistance among Mannheimia haemolytica and Pasteurella multocida from respiratory tract infections of cattle and swine

牛和猪呼吸道感染溶血曼海姆菌和多杀性巴氏杆菌大环内酯类药物耐药性的遗传基础、可转移性和共选择

• 批准号: 513529774
• 负责人: Professor Dr. Stefan P. Schwarz
• 金额: --
• 依托单位: Institut für Mikrobiologie und Tierseuchen (WE07)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/513529774?language=en
• 关键词: Genetic; basis; transferability; co; selection

Macrolides are commonly used antimicrobial agents for the therapy of respiratory tract infections in cattle and swine, in the pathogenesis of which Mannheimia haemolytica and Pasteurella multocida are significantly involved. Bacterial resistance to macrolides is mediated by various mechanisms, including enzymatic inactivation, chemical modification of the ribosomal target sites, active efflux as well as mutations in 23S rRNA or genes for ribosomal proteins. Macrolide resistance genes are often located on mobile genetic elements (MGEs), such as plasmids, transposons or integrative and conjugative elements (ICEs), which support their horizontal transfer across strain, species and genus boundaries. On these MGEs, macrolide resistance genes are commonly co-located with other antimicrobial resistance genes, which furthers their co-selection and persistence under the selective pressure also imposed by antimicrobial agents of other classes.In the national resistance monitoring programme GERM-Vet, a generally favourable resistance situation has been seen for M. haemolytica and P. multocida isolates from cattle and swine in Germany. However, macrolide-resistant isolates (M. haemolytica n=20; P. multocida n=102) have been detected at increasing frequencies during 2008 – 2020. In addition, bovine macrolide-resistant M. haemolytica and P. multocida isolates in Germany have recently been identified, in which the genetic basis of macrolide resistance was due to the resistance genes mef(C) and mph(G) as part of a novel ICE (M. haemolytica) or novel mutations in all six 23S rRNA operons (P. multocida). In addition, there are 4 macrolide-resistant M. haemolytica isolates from previous studies available, in which no known macrolide resistance mechanism could be identified.In the proposed project, we will on the one hand elucidate the genetic basis of macrolide resistance among the 122 M. haemolytica and P. multocida isolates from GERM-Vet. For this, whole genome analyses are planned which serve as a basis for all further experimental approaches, including the detection of macrolide resistance genes and macrolide resistance-mediating mutations. In addition, the analysis of MGEs potentially associated with the respective resistance genes, their structure and organization, content of additional resistance genes and their modes of transfer and host spectra are further key actions. On the other hand, we will perform in-depth analysis of the 4 M. haemolytica isolates with unknown macrolide resistance mechanisms for the genetic basis of resistance. This also includes the comparison with closely related macrolide-susceptible isolates on the basis of whole genome sequences, the analysis of outer membrane proteins as permeability barriers for macrolides, and transfer studies. Moreover, we will establish highly specific molecular identification systems for the novel macrolide resistance genes identified in this study in order to detect these genes quickly and reliably.

大环内酯类化合物是治疗牛、猪呼吸道感染常用的抗菌药物，其致病机制与溶血性曼氏杆菌和多杀性巴氏杆菌密切相关。细菌对大环内酯类抗生素的耐药性有多种机制，包括酶失活、核糖体靶位的化学修饰、主动外排以及23S rRNA或核糖体蛋白基因的突变。大环内酯类耐药基因通常位于可移动遗传元件(MGE)上，如质粒、转座子或整合结合元件(ICE)，它们支持大环内酯类耐药基因跨菌株、种和属的水平转移。在这些MGES上，大环内酯类耐药基因通常与其他抗菌素耐药基因共存，这进一步加强了它们在其他类别抗菌剂的选择压力下的共同选择和持久性。在国家耐药性监测计划Germ-Vet中，德国牛和猪的溶血分枝杆菌和多杀性巴氏杆菌分离株总体上呈现出良好的抗药性状况。然而，在2008-2020年间，检测到大环内酯类抗药性菌株(溶血分枝杆菌n=20；多杀性分枝杆菌n=102)的频率有所增加。此外，最近在德国发现了牛大环内酯类抗药性溶血分枝杆菌和多杀性巴氏杆菌分离株，其中大环内酯类抗药性的遗传基础是由于抗性基因mef(C)和mph(G)是一个新的ICE(溶血分枝杆菌)的一部分或所有6个23S rRNA操纵子(多杀性巴氏杆菌)的新突变。此外，目前已有4株溶血分枝杆菌对大环内酯类抗生素耐药，其耐药机制尚未明确。本研究将一方面阐明122株溶血分枝杆菌和多杀性巴氏杆菌对大环内酯类抗生素耐药的遗传基础。为此，计划进行全基因组分析，作为所有进一步实验方法的基础，包括检测大环内酯类耐药基因和大环内酯类耐药介导性突变。此外，对可能与各自抗性基因相关的MGES的分析、它们的结构和组织、附加抗性基因的含量及其转移方式和寄主光谱是进一步的关键行动。另一方面，我们将对4株大环内酯类抗生素耐药机制未知的溶血分枝杆菌的耐药基因基础进行深入分析。这还包括在全基因组序列的基础上与密切相关的大环内酯类敏感菌株的比较，作为大环内酯类通透性屏障的外膜蛋白的分析，以及转移研究。此外，我们还将为本研究中发现的新的大环内酯类耐药基因建立高度特异性的分子鉴定体系，以便快速、可靠地检测这些基因。