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广泛耐药临床肺炎克雷伯菌近肺炎亚种 ST1929 分离株的基因组和表型特征分析

 

Authors Ding J, Xu M, Xia Y , Kang X, Yu Y, Chang J, Hu Z, He P , Yao Y, Shen N, Tai W, Feng L

Received 12 September 2025

Accepted for publication 30 October 2025

Published 25 November 2025 Volume 2025:18 Pages 6153—6165

DOI https://doi.org/10.2147/IDR.S562899

Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Dr Hemant Joshi

Jiawei Ding,1,* Muli Xu,1,* Yuanzhi Xia,2,* Xilin Kang,3 Yan Yu,1 Jiyong Chang,1 Zidan Hu,1 Pei He,1 Yao Yao,1 Ni Shen,1 Wenlin Tai,4 Lei Feng1 

1Department of Medical Laboratory, The Affiliated Yan’an Hospital of Kunming Medical University, Kunming, Yunnan, People’s Republic of China; 2Department of Clinical Laboratory, The Second Affiliated Hospital of Xiamen Medical College, Xiamen, Fujian, People’s Republic of China; 3Department of Blood Transfusion, The Affiliated Yan’an Hospital of Kunming Medical University, Kunming, Yunnan, People’s Republic of China; 4Department of Medical Laboratory, The Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Wenlin Tai, Email taiwenlin@kmmu.edu.cn Lei Feng, Email fngj2004@163.com

Background: Klebsiella quasipneumoniae subsp. similipneumoniae is an emerging member of the K. pneumoniae complex that is often misidentified in routine diagnostics. Its clinical relevance and genomic characteristics remain poorly understood.
Methods: Four K. quasipneumoniae subsp. similipneumoniae isolates were collected from hospitalized patients in different wards and identified by whole-genome sequencing. Antimicrobial susceptibility testing was conducted using the broth microdilution method. Phylogenetic, comparative genomic, and plasmid transfer analyses were conducted to elucidate genetic relatedness and resistance mobility. Virulence phenotypes were assessed by measuring capsule production, biofilm formation, serum resistance, and in vivo pathogenicity in a Galleria mellonella infection model.
Results: All four isolates belonged to the novel ST1929-KL159 clonotype and exhibited an extensively drug-resistant phenotype, with resistance to β-lactams, carbapenems, fluoroquinolones, tigecycline, and trimethoprim-sulfamethoxazole. Amikacin was the only consistently active agent; one isolate showed high-level resistance to polymyxin B due to a premature stop mutation in mgrB (Gln30*). Genomic analysis revealed the coexistence of blaNDM-1 and the tigecycline resistance cluster tmexC2D2-toprJ2 on a IncU plasmid, which transferred efficiently to E. coli recipients. Comparative genomics demonstrated strong similarity to multidrug-resistant plasmids from diverse Enterobacterales. Phylogenetic analysis confirmed the global distribution of K. quasipneumoniae subsp. similipneumoniae but highlighted the rarity of ST1929, with close relatedness among the four isolates suggesting recent nosocomial transmission. Despite the absence of classical virulence genes, ST1929 exhibited enhanced biofilm formation, moderate capsule production, and intermediate serum resistance, but low virulence in the G. mellonella model.
Conclusion: This study provides the first description of K. quasipneumoniae subsp. similipneumoniae ST1929, an extensively drug-resistant lineage harboring blaNDM-1 and the tigecycline resistance cluster tmexC2D2-toprJ2 on a transferable IncU plasmid. The findings underscore the need for accurate detection and surveillance of this rare lineage.

Keywords: Klebsiella quasipneumoniae subsp. similipneumoniae, ST1929, resistance, tmexCD2-toprJ2, virulence