Molecular mechanisms of biocide and antibiotic resistance in Acinetobacter baumannii

鲍曼不动杆菌杀菌剂和抗生素耐药性的分子机制

• 批准号: RGPIN-2015-05550
• 负责人: Kumar, Ayush
• 金额: $ 2.19万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=656104
• 关键词: Molecular; mechanisms; biocide; antibiotic; resistance

Acinetobacter baumannii is a Gram-negative pathogen that is known for its ability to survive under harsh environmental conditions, including hospital settings. In addition to its impressive ability to adapt to inhospitable environments, A. baumannii is known for its high intrinsic resistance to antibiotics currently in use. Proton gradient-dependent efflux systems belonging to the Resistance-Nodulation-Division (RND) family are important factors contributing to the intrinsic antibiotic resistance of A. baumannii. Three different RND pumps: AdeABC, AdeFGH, and AdeIJK, have been characterized in A. baumannii. While the antibiotic substrates of these pumps have been well described in the literature, regulatory mechanisms that control the expression of these pumps are not very well understood. In addition, while there is a general consensus that the efflux of antibiotics is not their primary role, physiological function(s) of these pumps in A. baumannii remain unknown. In this application, we propose to seek answers to these two questions. We have isolated a triclosan resistant mutant of A. baumannii that overexpresses the AdeFGH and AdeIJK pumps. Triclosan targets the fatty acid biosynthesis pathway by inhibiting the action of fatty acid biosynthesis enzyme FabI, and we observed that the expression of fabI is increased in this mutant as well. In this application we propose to examine if the observed overexpression of RND pumps and fabI is linked in this mutant, and also if perturbations in fatty acid biosynthesis can lead to the overexpression of RND efflux pumps. We have analyzed the sequences of known regulators of both the AdeFGH and AdeIJK pumps and have found no mutations. This suggests the role of other regulators that control the expression of the AdeFGH and AdeIJK RND pumps in A. baumannii. By conducting whole genome sequencing, we have identified eleven different genes in the mutant strain that contain mutations when compared to a type strain. In this application we propose to study the role of these genes in the expression of RND pumps as well as fabI. In addition, we also propose to characterize two novel RND pumps (A1S_3217 and A1S_0535) in A. baumannii, whose expression was also altered in the triclosan-resistant mutant. The proposed research program will therefore not only provide new insights into the mechanisms that regulate the expression of RND pumps, but will also investigate the intriguing link between membrane lipids and antibiotic resistance.

鲍曼尼（Baumannii）的杆菌是一种革兰氏阴性的病原体，以其在包括医院环境在内的恶劣环境条件下生存的能力而闻名。除了适应不荒的环境的令人印象深刻的能力外，鲍曼尼曲霉还以其对目前正在使用的抗生素的高内在耐药性而闻名。质子梯度依赖性外排系统属于抗性 - 结构分割（RND）家族是造成鲍曼尼曲霉固有抗生素耐药性的重要因素。三种不同的RND泵：ADEABC，ADEFGH和ADEIJK在A. Baumannii中进行了特征。尽管这些泵的抗生素底物在文献中得到了很好的描述，但控制这些泵表达的调节机制并不十分了解。此外，尽管一般共识，即抗生素的排出不是其主要作用，但鲍曼尼a。这些泵的生理功能仍然未知。在此应用程序中，我们建议寻求这两个问题的答案。我们已经隔离了A. baumannii的三氯生抗药性突变体，该突变体过表达了Adefgh和Adeijk泵。 Triclosan通过抑制脂肪酸生物合成酶Fabi的作用来靶向脂肪酸生物合成途径，我们观察到该突变体中Fabi的表达也会增加。在此应用中，我们建议检查该突变体中观察到的RND泵和Fabi的过表达，以及脂肪酸生物合成中的扰动是否会导致RND外排泵的过表达。我们已经分析了Adefgh和Adeijk泵的已知调节剂的序列，但没有发现突变。这表明其他调节剂控制A. Baumannii中Adefgh和Adeijk Rnd泵的表达的作用。通过进行整个基因组测序，我们已经确定了突变菌株中的11种不同的基因，这些基因与类型菌株相比包含突变。在此应用中，我们建议研究这些基因在RND泵和Fabi表达中的作用。此外，我们还建议在A. baumannii中表征两个新型RND泵（A1S_3217和A1S_0535），其表达在三氯糖耐药突变体中也发生了变化。因此，拟议的研究计划不仅将提供有关调节RND泵表达的机制的新见解，而且还将研究膜脂质与抗生素耐药性之间的有趣联系。