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Characterization of Plasmid Co-Harboring NDM-1 and SHV-12 from a Multidrug-Resistant Citrobacter freundii Strain ZT01-0079 in China

Authors Zhang T, Lin Y, Li P, Li Z, Liu X, Li J, Li L, Wang K, Liu Z, Li P, Lu L, Wang H

Received 12 January 2021

Accepted for publication 23 February 2021

Published 9 March 2021 Volume 2021:14 Pages 947—952


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Dr Héctor M. Mora-Montes

Tingyan Zhang,1,2,* Yanfeng Lin,2,3,* Peihan Li,2,3,* Zhonghong Li,2 Xiong Liu,2 Jinhui Li,2 Lizhong Li,2 Kaiying Wang,2,3 Zhongdong Liu,1 Peng Li,2 Lanfen Lu,4 Hongyan Wang1

1School of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou, People’s Republic of China; 2Chinese PLA Center for Disease Control and Prevention, Beijing, People’s Republic of China; 3Academy of Military Medical Sciences, Beijing, People’s Republic of China; 4Department of Laboratory Diagnosis, Sun Yat-Sen University Affiliated Zhongshan Hospital, Zhongshan, Guangdong, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Peng Li; Hongyan Wang Email [email protected]; [email protected]

Background: The emergence of multidrug-resistant Citrobacter freundii poses daunting challenges to the treatment of clinical infections. The purpose of this study was to characterize the genome of a C. freundii strain with an IncX3 plasmid encoding both the blaNDM-1 and blaSHV-12 genes.
Methods: Strain ZT01-0079 was isolated from a clinical urine sample. The Vitek2 system was used for identification and antimicrobial susceptibility testing. The presence of blaNDM-1 was detected by PCR and sequencing. Conjugation experiments and Southern blotting were performed to determine the transferability of the blaNDM-1- carrying plasmid. Nanopore and Illumina sequencing were performed to better understand the genomic characteristics of the strain.
Results: Strain ZT01-0079 was identified as C. freundii, and the coexistence of blaNDM-1 and multiple drug resistance genes was confirmed. Electrophoresis and Southern blotting showed that blaNDM-1 was located on a ∼ 53kb IncX3 plasmid. The NDM-1-encoding plasmid was successfully transferred at a frequency of 1.68× 10− 3. Both the blaNDM-1 and blaSHV-12 genes were located on the self-transferable IncX3 plasmid.
Conclusion: The rapid spread of the IncX3 plasmid highlights the importance of continuous monitoring of the prevalence of NDM-1-encoding Enterobacteriaceae. Mutations of existing carbapenem resistance genes will bring formidable challenges to clinical treatment.

Keywords: C. freundii, whole-genome sequencing, genomics analysis

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