Characterisation of in vitro resistance selection against second-/last-line antibiotics in methicillin-resistant Staphylococcus aureus ATCC 43300 strain.

IF 3.7 Q2 INFECTIOUS DISEASES
JAC-Antimicrobial Resistance Pub Date : 2025-06-23 eCollection Date: 2025-06-01 DOI:10.1093/jacamr/dlaf108
Anggia Prasetyoputri, Miranda E Pitt, Minh Duc Cao, Soumya Ramu, Angela Kavanagh, Alysha G Elliott, Devika Ganesamoorthy, Ian R Monk, Timothy P Stinear, Matthew A Cooper, Lachlan J M Coin, Mark A T Blaskovich
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Abstract

Background and objectives: The increasing occurrence of MRSA clinical isolates harbouring reduced susceptibility to mainstay antibiotics has escalated the use of second and last line antibiotics. Hence, it is critical to evaluate the likelihood of MRSA developing clinical resistance to these antibiotics. Our study sought to characterize the development of resistance to vancomycin (VAN), daptomycin (DAP) and linezolid (LZD) in MRSA ATCC 43300 in vitro and further determine the mechanisms underpinning resistance.

Methods: MRSA was exposed to increasing concentrations of VAN, DAP and LZD for 20 days, with eight replicates for each antibiotic conducted in parallel. The resulting day 20 (D20) isolates were subjected to antimicrobial susceptibility testing, whole genome sequencing, autolysis assays, and growth curves to determine bacterial fitness.

Results: Exposure to VAN or LZD for 20 days resulted in a subtle 2-fold increase in the MIC, whereas DAP exposure yielded DAP-non-susceptible isolates with up to 16-fold MIC increase. The MIC increase was accompanied by variable changes in relative fitness and reduced resistance to autolysis in some isolates. D20 isolates harboured mutations in genes commonly associated with resistance to the respective antibiotics (e.g. walK for VAN, mprF and rpoB for DAP, rplC for LZD), along with several previously unreported variants. Introduction of key mutations to these identified genes in the parental strain via allelic exchange confirmed their role in the development of resistance.

Conclusions: In vitro selection against VAN, DAP or LZD resulted in the acquisition of mutations similar to those correlated with clinical resistance, including the associated phenotypic alterations.

耐甲氧西林金黄色葡萄球菌ATCC 43300菌株对二线/最后一线抗生素的体外耐药性选择特征
背景和目的:耐甲氧西林金黄色葡萄球菌临床分离株对主要抗生素的敏感性降低,这使得二线和一线抗生素的使用不断增加。因此,评估MRSA对这些抗生素产生临床耐药性的可能性至关重要。本研究旨在表征MRSA ATCC 43300对万古霉素(VAN)、达托霉素(DAP)和利奈唑胺(LZD)的体外耐药发展,并进一步确定耐药机制。方法:增加VAN、DAP和LZD的浓度,将MRSA暴露20 d,每种抗生素平行进行8个重复。对得到的第20天(D20)分离株进行抗菌药敏试验、全基因组测序、自溶试验和生长曲线测定细菌适合度。结果:暴露于VAN或LZD 20天导致MIC轻微增加2倍,而DAP暴露使DAP不敏感的分离株MIC增加高达16倍。在一些分离株中,MIC的增加伴随着相对适应度的可变变化和对自溶的抵抗力降低。D20分离株含有通常与各自抗生素耐药相关的基因突变(例如,VAN的walK, DAP的mprF和rpoB, LZD的rplC),以及一些以前未报道的变体。通过等位基因交换,在亲本菌株中引入这些鉴定基因的关键突变,证实了它们在抗性发展中的作用。结论:体外选择抗VAN、DAP或LZD导致获得与临床耐药相关的突变,包括相关的表型改变。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
5.30
自引率
0.00%
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审稿时长
16 weeks
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