Investigation of Mutations and Expression Level of GraSR and WalKR Systems Associated with Vancomycin Non-Susceptibility in Methicillin-Resistant Staphylococcus aureus

IF 0.4 4区生物学 Q4 BIOCHEMISTRY & MOLECULAR BIOLOGY

Molecular Genetics, Microbiology and Virology Pub Date : 2024-07-09 DOI:10.3103/s0891416824700071

Mahsa Aghaei, Leila Asadpour, Amir Arasteh

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引用次数: 0

Abstract

The present study was conducted to investigate the frequency of antibiotic resistance genes and mutations and expression level of GraSR and WalKR systems associated with vancomycin non-susceptibility in methicillin-resistant Staphylococcus aureus. In 2022, a total of 200 S. aureus isolates were investigated in terms of methicillin resistance and reduced susceptibility to vancomycin. In vitro antibiotic susceptibility testing of MRSA isolates and the frequency of 12 antibiotic resistance genes were assessed using disk diffusion and PCR technique, respectively. Amino acid alteration in two-component regulatory systems including GraSR and WalKR in VISA isolates were determined by PCR-sequencing, the expression of these systems was analysed by RT-qPCR whereas agr- and spa-typing were used for molecular typing of these isolates. Overall, 125 (62.5%) isolates were methicillin-resistant and 75% were multiple-antibiotic-resistant. Vancomycin was the most efficient antibiotic against the isolates and blaZ gene was shown to be the most common (96.66%) gene among MRSA. A highly diverse amino acid substitution was observed in WalKR and GraSR in VISA and VRSA strains. Interestingly, 100% of vancomycin non-susceptible strains had the D148Q substitution in the GraR and I59L was the most common change in GraS. VISA isolates showed higher walR expression levels than the mean level of their progenitor VSSA. Agr types 1 and 3 and spa types t030, t421, t037, t325, t084 and t005 were detected among VISA isolates. The present results indicate high frequency of antibiotic resistance genes in methicillin-resistant S. aureus isolates. Furthermore, our results suggest that GraS, WalK, and WalR are important in vancomycin non- susceptibility and also these findings support the need for future surveillance studies to better elucidate vancomycin resistance in MRSA strains.

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耐甲氧西林金黄色葡萄球菌中与万古霉素不敏感性相关的 GraSR 和 WalKR 系统突变及表达水平研究

本研究旨在调查耐甲氧西林金黄色葡萄球菌中与万古霉素不敏感性相关的抗生素耐药基因和突变的频率以及 GraSR 和 WalKR 系统的表达水平。2022 年，共对 200 个金黄色葡萄球菌分离株进行了耐甲氧西林和对万古霉素敏感性降低方面的研究。采用盘扩散和 PCR 技术分别对 MRSA 分离物的体外抗生素敏感性测试和 12 种抗生素耐药基因的频率进行了评估。通过 PCR 测序确定了 VISA 分离物中包括 GraSR 和 WalKR 在内的双组分调控系统的氨基酸变化，并通过 RT-qPCR 分析了这些系统的表达情况，同时使用 agr- 和 spa- 类型对这些分离物进行分子分型。总体而言，125 个（62.5%）分离株对甲氧西林耐药，75%对多种抗生素耐药。万古霉素是对分离株最有效的抗生素，而 blaZ 基因是 MRSA 中最常见的基因（96.66%）。在 VISA 和 VRSA 菌株的 WalKR 和 GraSR 中观察到了高度多样化的氨基酸替代。有趣的是，对万古霉素不敏感的菌株 100%在 GraR 中出现了 D148Q 替代，而 I59L 是 GraS 中最常见的变化。VISA 分离物的 walR 表达水平高于其祖先 VSSA 的平均水平。在 VISA 分离物中检测到 Agr 类型 1 和 3 以及 spa 类型 t030、t421、t037、t325、t084 和 t005。本研究结果表明，耐甲氧西林金黄色葡萄球菌分离物中抗生素耐药基因的频率很高。此外，我们的研究结果表明，GraS、WalK 和 WalR 在万古霉素非敏感性中起着重要作用，这些研究结果也支持了今后开展监测研究的必要性，以更好地阐明 MRSA 菌株对万古霉素的耐药性。

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来源期刊

Molecular Genetics, Microbiology and Virology BIOCHEMISTRY & MOLECULAR BIOLOGY-MICROBIOLOGY

CiteScore

0.70

自引率

0.00%

发文量

审稿时长

>12 weeks

期刊介绍： Molecular Genetics, Microbiology and Virology is a journal that covers most topical theoretical and applied problems of molecular genetics of pro- and eukaryotic organisms, molecular microbiology and molecular virology. An important part the journal assigns to investigations of the genetic apparatus of microorganisms, searching for forms of genetic exchange, genetic mapping of pathogenic causative agents, to ascertainment of the structure and functions of extrachromosomal factors of heredity and migratory genetic elements, to theoretical studies into the mechanisms of genetic regulation. The journal publishes results of research on molecular and genetic bases of an eukaryotic cell, functioning of chromosomes and chromatin, nature of genetic changes in malignization and a set of hereditary diseases. On the pages of the journal there is covered the formulation of molecular bases of virology including issues of integration of viral and cellular genomes, and issues of persistence. The journal plans to put materials on genetic engineering, envisaging synthesis and isolation of genes from natural reservoirs, creation of plasmid- and virus-based vector, production of recombinant DNA molecules, the creation of Gene Banks for Microbes, animals, and human; and also on biotechnological production of hormones, components of antiviral vaccines, diagnostic and therapeutic preparations.