IF 5.1 1区 生物学 Q1 MICROBIOLOGY
mBio Pub Date : 2024-12-20 DOI:10.1128/mbio.02982-24
Luyuan Nong, Martijs Jonker, Wim de Leeuw, Meike T Wortel, Benno Ter Kuile
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引用次数: 0

摘要

β-内酰胺类抗生素是人类和兽医保健中应用最多的抗菌药物。因此,β-内酰胺耐药性是一个主要的健康问题。AmpC β-内酰胺酶的基因扩增是导致大肠杆菌产生新的β-内酰胺耐药性的主要原因。然而,扩增的时间过程和伴随的 DNA 变异尚不清楚。在此,我们研究了在逐步提高阿莫西林浓度诱导耐药性演变的过程中,ampC 扩增和 ampC 启动子突变的进展。AmpC 启动子突变发生在第 2 天,而大约 8 倍的扩增发生在阿莫西林暴露超过 6 天之后。扩增与启动子突变相结合,22 天后 ampC mRNA 水平平均提高了 200 倍。在野生型(WT)和 ampC 基因互补株(CompA)的抗性诱导后,在扩增连接处发现了 IS1 插入,但在∆ampC 中没有发现,这表明扩增依赖于移动遗传因子的转座。为了阐明基因突变与 ampC 扩增之间的相关性,对 WT、ΔampC 和 CompA 在抗性进化过程中获得的 DNA 突变进行了分析。与进化后的∆ampC相比,进化后的WT不存在几种导致抗性的突变,而在应激反应中积累了更多的突变。耐阿莫西林的 ∆ampC 在原始 ampC 位置附近的片段没有出现扩增,但在另一个位置出现了大量复制或三倍复制,这表明复制基因在耐药性产生过程中起着重要作用。重要意义阿莫西林是治疗细菌感染最常用的抗菌素。当长期接触阿莫西林并逐步增加接触量时,含有 ampC 的 DNA 片段会被扩增,从而产生耐药性。这些含 ampC 的片段已在广谱 beta-内酰胺酶质粒中被发现,而广谱 beta-内酰胺酶质粒被认为是产生 beta-内酰胺耐药性的主要原因。在本研究中,我们记录了在阿莫西林耐药性从头演化过程中,ampC 转录增强的两个重要因素--ampC 扩增和 ampC 启动子突变的时间过程。我们提出,转座子 IS1 对扩增 ampC 区域有贡献,sigma 因子 70 对 ampC 的过度表达有调节作用,这些因素的结合构成了 ampC 扩增的推定机制的支柱。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Progression of ampC amplification during de novo amoxicillin resistance development in E. coli.

Beta-lactam antibiotics are the most applied antimicrobials in human and veterinarian health care. Hence, beta-lactam resistance is a major health problem. Gene amplification of AmpC beta-lactamase is a main contributor to de novo β-lactam resistance in Escherichia coli. However, the time course of amplification and the accompanying DNA mutations are unclear. Here, we study the progression of ampC amplification and ampC promoter mutations during the evolution of resistance induced by stepwise increasing amoxicillin concentrations. AmpC promoter mutations occurred by day 2, while the approximately eight-fold amplification occurred after more than 6 days of amoxicillin exposure. The combination of the amplification and the promoter mutations increased the ampC mRNA level by an average factor of 200 after 22 days. An IS1 insertion is identified in the amplification junction after resistance induction in the wild type (WT) and the ampC gene complementation strain (CompA), but not in ∆ampC, suggesting that the amplification depends on mobile genetic element transposition. In order to elucidate the correlation between gene mutations and ampC amplification, the DNA mutations acquired during resistance evolution by the WT, ∆ampC, and CompA were analyzed. Compared to evolved ∆ampC, several resistance-causing mutations are absent in evolved WT, while more mutations accumulated in stress response. The amoxicillin-resistant ∆ampC did not show amplification of the fragment around the original ampC position but exhibited a large duplication or triplication at another position, suggesting the essential role of the duplicated genes in resistance development.IMPORTANCEAmoxicillin is the most used antimicrobial against bacterial infections. DNA fragments containing ampC are amplified upon prolonged and stepwise increasing exposure to amoxicillin, causing resistance. These ampC-containing fragments have been identified in extended-spectrum beta-lactamase plasmids, which are considered the main cause of beta-lactam resistance. In this study, we document the time course of two important factors for ampC transcription enhancement, ampC amplification and ampC promoter mutations, during de novo amoxicillin resistance evolution. We propose that the transposon IS1 contributes to the amplification ampC region, that the sigma factor 70 regulates ampC overexpression, and that these combined form the backbone of a putative mechanism for ampC amplification.

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来源期刊
mBio
mBio MICROBIOLOGY-
CiteScore
10.50
自引率
3.10%
发文量
762
审稿时长
1 months
期刊介绍: mBio® is ASM''s first broad-scope, online-only, open access journal. mBio offers streamlined review and publication of the best research in microbiology and allied fields.
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