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Background <p><i>Serratia marcescens</i> is a common opportunistic pathogen in hospitals. Its carbapenem-resistant strains, especially those carrying the <i>bla</i><sub>KPC−2</sub> gene, pose a serious challenge to clinical infection treatment.</p> Methods <p>In this study, we identified 14 strains that were positive for <i>bla</i><sub>KPC−2</sub> from tertiary hospitals in Zhejiang Province, China, through phenotypic tests and sequencing. We also incorporated data from the GenBank public database, resulting in a total of 2005 <i>Serratia</i> strains included for bioinformatic analysis.</p> Results <p>A total of 121 strains (6.03%) were found to carry <i>bla</i><sub>KPC−2</sub>. These positive isolates predominantly originated from China (76.86%) and the United States (14.88%), with the vast majority (94.21%) identified as clinical isolates. The period from 2018 to 2019 was relatively active for global data collection, particularly for samples from the Yangtze River Delta region in China. Phylogenetic analysis classified the 121 strains carrying <i>bla</i><sub>KPC−2</sub> into six evolutionary clusters (Cluster I-VI), with most strains grouped in Cluster V and Cluster VI. Cluster VI, largely consisting of ST595, was predominantly composed of Chinese isolates. In contrast, Cluster V displayed coexistence of diverse sequence types and geographic origins. Resistance gene profiling identified 52 antimicrobial resistance genes. Besides <i>bla</i><sub>KPC−2</sub>, three strains were also positive for <i>bla</i><sub>NDM−1</sub>. Additionally, a novel plasmid lineage was identified and designated as pK17-KPC/pK1030-KPC (approximately 87&#xa0;kb). Its replication initiator gene, <i>repA1</i>, showed low homology (≤ 93.25%) to known plasmids. This plasmid has a complex structure and carries a <i>bla</i><sub>KPC−2</sub> resistance module mediated by unit transposon ΔTn<i>6296</i>.</p> Conclusions <p>This study systematically describes the global transmission patterns and molecular genetic features of <i>Serratia marcescens</i> strains carrying <i>bla</i><sub>KPC−2</sub>. It reveals the structural characteristics of a novel plasmid harboring <i>bla</i><sub>KPC−2</sub> and provides key scientific evidence for clinical prevention and control of antimicrobial resistance.</p>

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Evolutionary genomics of KPC-2-producing Serratia marcescens and characterization of a novel blaKPC−2-harboring plasmid

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年12月26日

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  • Yali Zheng,
  • Ying Jing,
  • Yan Zhang,
  • Jin Zhang,
  • Jianbo Ye,
  • Huimin Chen,
  • Yuting Jin,
  • Jiayu He,
  • Yu Zhang,
  • Xinhua Luo

摘要

Background

Serratia marcescens is a common opportunistic pathogen in hospitals. Its carbapenem-resistant strains, especially those carrying the blaKPC−2 gene, pose a serious challenge to clinical infection treatment.

Methods

In this study, we identified 14 strains that were positive for blaKPC−2 from tertiary hospitals in Zhejiang Province, China, through phenotypic tests and sequencing. We also incorporated data from the GenBank public database, resulting in a total of 2005 Serratia strains included for bioinformatic analysis.

Results

A total of 121 strains (6.03%) were found to carry blaKPC−2. These positive isolates predominantly originated from China (76.86%) and the United States (14.88%), with the vast majority (94.21%) identified as clinical isolates. The period from 2018 to 2019 was relatively active for global data collection, particularly for samples from the Yangtze River Delta region in China. Phylogenetic analysis classified the 121 strains carrying blaKPC−2 into six evolutionary clusters (Cluster I-VI), with most strains grouped in Cluster V and Cluster VI. Cluster VI, largely consisting of ST595, was predominantly composed of Chinese isolates. In contrast, Cluster V displayed coexistence of diverse sequence types and geographic origins. Resistance gene profiling identified 52 antimicrobial resistance genes. Besides blaKPC−2, three strains were also positive for blaNDM−1. Additionally, a novel plasmid lineage was identified and designated as pK17-KPC/pK1030-KPC (approximately 87 kb). Its replication initiator gene, repA1, showed low homology (≤ 93.25%) to known plasmids. This plasmid has a complex structure and carries a blaKPC−2 resistance module mediated by unit transposon ΔTn6296.

Conclusions

This study systematically describes the global transmission patterns and molecular genetic features of Serratia marcescens strains carrying blaKPC−2. It reveals the structural characteristics of a novel plasmid harboring blaKPC−2 and provides key scientific evidence for clinical prevention and control of antimicrobial resistance.