Occurrence of Serratia marcescens Carrying blaIMP-26 and mcr-9 in Southern China: New Insights in the Evolution of Megaplasmid IMP-26

Yuxia Zhong; Wanting Liu; Peibo Yuan; Ling Yang; Zhenbo Xu; Dingqiang Chen

doi:10.3390/antibiotics11070869

Occurrence of Serratia marcescens Carrying bla_IMP-26 and mcr-9 in Southern China: New Insights in the Evolution of Megaplasmid IMP-26

Antibiotics (Basel). 2022 Jun 28;11(7):869. doi: 10.3390/antibiotics11070869.

Authors

Yuxia Zhong¹, Wanting Liu¹, Peibo Yuan¹, Ling Yang², Zhenbo Xu^{3

4

5}, Dingqiang Chen¹

Affiliations

¹ Microbiome Medicine Center, Department of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
² Department of Laboratory Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China.
³ School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Engineering Research Center of Starch and Vegetable Protein Processing Ministry of Education, South China University of Technology, Guangzhou 510640, China.
⁴ Department of Civil and Environmental Engineering, University of Maryland, College Park, MD 20742, USA.
⁵ Research Institute for Food Nutrition and Human Health, Guangzhou 510640, China.

Abstract

The spread of multidrug-resistant enterobacteria strains has posed a significant concern in public health, especially when the strain harbors metallo-beta-lactamase (MBL)-encoding and mobilized colistin resistance (mcr) genes as such genetic components potentially mediate multidrug resistance. Here we report an IncHI2/2A plasmid carrying bla_IMP-26 and mcr-9 in multidrug-resistant Serratia marcescens human isolates YL4. Antimicrobial susceptibility testing was performed by the broth microdilution method. According to the results, S. marcescens YL4 was resistant to several antimicrobials, including β-lactams, fluorquinolones, sulfanilamide, glycylcycline, and aminoglycosides, except for amikacin. To investigate the plasmid further, we conducted whole-genome sequencing and sequence analysis. As shown, S. marcescens YL4 possessed a circular chromosome with 5,171,477 bp length and two plasmids, pYL4.1 (321,744 bp) and pYL4.2 (46,771 bp). Importantly, sharing high similarity with plasmids pZHZJ1 and pIMP-26, pYL4.1 has an IncHI2/2A backbone holding a variable region containing bla_IMP-26, mcr-9, and two copies of bla_TEM-1B. After comprehensively comparing relevant plasmids, we proposed an evolutionary pathway originating from ancestor pZHZJ1. Then, via an acquisition of the mcr-9 element and a few recombination events, this plasmid eventually evolved into pYL4.1 and pIMP-26 through two different pathways. In addition, the phage-like plasmid pYL4.2 also carried a bla_TEM-1B gene. Remarkably, this study first identified a multidrug-resistant S. marcescens strain co-harboring bla_IMP-26 and mcr-9 on a megaplasmid pYL4.1 and also included a proposed evolutionary pathway of epidemic megaplasmids carrying bla_IMP-26.

Keywords: Serratia marcescens; blaIMP-26; evolutionary pathway; mcr-9; megaplasmids IMP-26; multidrug resistance.

Abstract

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