A novel mutation of ramR involved in tigecycline resistance in Klebsiella pneumoniae

ABSTRACT This study aims to investigate the novel potential tigecycline resistance mechanism in Klebsiella pneumoniae and provide new insights for the clinical treatment of infections caused by carbapenem-resistant Klebsiella pneumoniae. In vitro experiments were conducted to induce tigecycline resi...

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Main Authors: Yuyao Xu, Qi Chen, Chenhao Zhao, Xin Ma, Lei Wang, Feinan Qian, Xiangyu Guan, Hong Du, Haifang Zhang
Format: Article
Language:English
Published: American Society for Microbiology 2025-06-01
Series:Microbiology Spectrum
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Online Access:https://journals.asm.org/doi/10.1128/spectrum.03204-24
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author Yuyao Xu
Qi Chen
Chenhao Zhao
Xin Ma
Lei Wang
Feinan Qian
Xiangyu Guan
Hong Du
Haifang Zhang
author_facet Yuyao Xu
Qi Chen
Chenhao Zhao
Xin Ma
Lei Wang
Feinan Qian
Xiangyu Guan
Hong Du
Haifang Zhang
author_sort Yuyao Xu
collection DOAJ
description ABSTRACT This study aims to investigate the novel potential tigecycline resistance mechanism in Klebsiella pneumoniae and provide new insights for the clinical treatment of infections caused by carbapenem-resistant Klebsiella pneumoniae. In vitro experiments were conducted to induce tigecycline resistance in Klebsiella pneumoniae, simulating potential genetic mutations that may arise under the selective pressure of tigecycline in clinical settings. Next-generation sequencing and real-time quantitative PCR (RT-qPCR) were employed to analyze bacterial genomic mutations and the transcription of related genes, respectively. Gene knockout technology, broth microdilution method, and resistance stability tests were utilized to further validate the function of the identified gene mutation sites. A novel two-base pair deletion mutation (position 517-518) in the ramR gene (g. 517_518 del) was identified in Klebsiella pneumoniae strains cultured in broth medium containing progressively increasing concentrations of tigecycline (4, 8, and 16 mg/L). The impact of this mutation on tigecycline resistance was characterized. The RT-qPCR analysis revealed a consistent upregulation of ramR expression across all tigecycline-induced strains, with significant elevation observed at various concentrations (0.5, 1, 2, 4, 8, and 16 mg/L). Furthermore, the g. 517_518 del mutation in ramR was associated with sustained tigecycline resistance. This study illustrated a novel ramR mutation, leading to tigecycline resistance in Klebsiella pneumoniae.IMPORTANCEIn this study, a novel missense mutation (g. 517_518 del GC) was detected in the ramR of tigecycline-induced Klebsiella pneumoniae, which was conducted in vitro, and the effects of anti-tigecycline caused by this mutation in ramR were confirmed. A high expression of ramR was observed in all tigecycline-induced strains. In addition, g. 517_518 del GC in ramR maintained tigecycline resistance. In summary, we illustrated a novel mutation of ramR, leading to tigecycline resistance in Klebsiella pneumoniae.
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spelling doaj-art-996a7700d2ad4e5e86924cd94690c0af2025-08-20T03:07:32ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972025-06-0113610.1128/spectrum.03204-24A novel mutation of ramR involved in tigecycline resistance in Klebsiella pneumoniaeYuyao Xu0Qi Chen1Chenhao Zhao2Xin Ma3Lei Wang4Feinan Qian5Xiangyu Guan6Hong Du7Haifang Zhang8Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, ChinaDepartment of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, ChinaDepartment of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, ChinaDepartment of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, ChinaDepartment of Laboratory Medicine, The Affiliated Zhangjiagang TCM Hospital of Yangzhou University, Zhangjiagang, Jiangsu, ChinaDepartment of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, ChinaDepartment of Laboratory Medicine, The Affiliated Zhangjiagang TCM Hospital of Yangzhou University, Zhangjiagang, Jiangsu, ChinaDepartment of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, ChinaDepartment of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, ChinaABSTRACT This study aims to investigate the novel potential tigecycline resistance mechanism in Klebsiella pneumoniae and provide new insights for the clinical treatment of infections caused by carbapenem-resistant Klebsiella pneumoniae. In vitro experiments were conducted to induce tigecycline resistance in Klebsiella pneumoniae, simulating potential genetic mutations that may arise under the selective pressure of tigecycline in clinical settings. Next-generation sequencing and real-time quantitative PCR (RT-qPCR) were employed to analyze bacterial genomic mutations and the transcription of related genes, respectively. Gene knockout technology, broth microdilution method, and resistance stability tests were utilized to further validate the function of the identified gene mutation sites. A novel two-base pair deletion mutation (position 517-518) in the ramR gene (g. 517_518 del) was identified in Klebsiella pneumoniae strains cultured in broth medium containing progressively increasing concentrations of tigecycline (4, 8, and 16 mg/L). The impact of this mutation on tigecycline resistance was characterized. The RT-qPCR analysis revealed a consistent upregulation of ramR expression across all tigecycline-induced strains, with significant elevation observed at various concentrations (0.5, 1, 2, 4, 8, and 16 mg/L). Furthermore, the g. 517_518 del mutation in ramR was associated with sustained tigecycline resistance. This study illustrated a novel ramR mutation, leading to tigecycline resistance in Klebsiella pneumoniae.IMPORTANCEIn this study, a novel missense mutation (g. 517_518 del GC) was detected in the ramR of tigecycline-induced Klebsiella pneumoniae, which was conducted in vitro, and the effects of anti-tigecycline caused by this mutation in ramR were confirmed. A high expression of ramR was observed in all tigecycline-induced strains. In addition, g. 517_518 del GC in ramR maintained tigecycline resistance. In summary, we illustrated a novel mutation of ramR, leading to tigecycline resistance in Klebsiella pneumoniae.https://journals.asm.org/doi/10.1128/spectrum.03204-24tigecyclineramRKlebsiella pneumoniaeresistance
spellingShingle Yuyao Xu
Qi Chen
Chenhao Zhao
Xin Ma
Lei Wang
Feinan Qian
Xiangyu Guan
Hong Du
Haifang Zhang
A novel mutation of ramR involved in tigecycline resistance in Klebsiella pneumoniae
Microbiology Spectrum
tigecycline
ramR
Klebsiella pneumoniae
resistance
title A novel mutation of ramR involved in tigecycline resistance in Klebsiella pneumoniae
title_full A novel mutation of ramR involved in tigecycline resistance in Klebsiella pneumoniae
title_fullStr A novel mutation of ramR involved in tigecycline resistance in Klebsiella pneumoniae
title_full_unstemmed A novel mutation of ramR involved in tigecycline resistance in Klebsiella pneumoniae
title_short A novel mutation of ramR involved in tigecycline resistance in Klebsiella pneumoniae
title_sort novel mutation of ramr involved in tigecycline resistance in klebsiella pneumoniae
topic tigecycline
ramR
Klebsiella pneumoniae
resistance
url https://journals.asm.org/doi/10.1128/spectrum.03204-24
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