Infection and Drug Resistance (Jun 2024)

Emergence of an Extensive Drug Resistant Citrobacter portucalensis Clinical Strain Harboring blaSFO-1, blaKPC-2, and blaNDM-1

  • Guo K,
  • Zhao Z,
  • Yang Y,
  • Jiang X,
  • Xu H,
  • Tao F,
  • Xu Y,
  • Liu W

Journal volume & issue
Vol. Volume 17
pp. 2273 – 2283

Abstract

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Kexin Guo,1,* Zanzan Zhao,1,* Yu Yang,1 Xiawei Jiang,1 Hao Xu,2 Fangfang Tao,1 Ye Xu,1 Wenhong Liu1 1School of Basic Medical Sciences, Zhejiang Chinese Medical University, Hangzhou, People’s Republic of China; 2Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Wenhong Liu, School of Basic Medical Sciences, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, People’s Republic of China, Email [email protected]: To explore the plasmid characteristics and transfer mechanisms of an extensive drug resistant (XDR) clinical isolate, Citrobacter portucalensis L2724hy, co-producing blaSFO-1, blaNDM-1, and blaKPC-2.Methods: Species confirmation of L2724hy was achieved through 16S rRNA sequencing and Average Nucleotide Identity (ANI) analysis. Antimicrobial susceptibility testing (AST) employed the agar dilution and micro broth dilution methods. Identification of resistance genes was carried out by PCR and whole-genome sequencing (WGS). Essential resistance gene locations were verified by S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and southern hybridization experiments. Subsequent WGS data analysis delved into drug resistance genes and plasmids.Results: The confirmation of the strain L2724hy as an extensive drug-resistant Citrobacter portucalensis, resistant to almost all antibiotics tested except polymyxin B and tigecycline, was achieved through 16S rRNA sequencing, ANI analysis and AST results. WGS and subsequent analysis revealed L2724hy carrying blaSFO-1, blaNDM-1, and blaKPC-2 on plasmids of various sizes. The uncommon ESBL gene blaSFO-1 coexists with the fosA3 gene on an IncFII plasmid, featuring the genetic environment IS 26-fosA3-IS 26-ampR-blaSFO-1-IS 26. The blaNDM-1 was found on an IncX3 plasmid, coexisting with blaSHV-12, displaying the sequence IS 5-IS 3000-IS 3000-Tn 2-blaNDM-1-ble-trpF-dsbD-cutA-gros-groL, lacking ISAa125. The blaKPC-2 is located on an unclassified plasmid, exhibiting the sequence Tn 2-tnpR-ISKpn27-blaKPC-2-ISKpn6-korC. Conjugation assays confirmed the transferability of both blaNDM-1 and blaKPC-2.Conclusion: We discovered the coexistence of blaSFO-1, blaNDM-1, and blaKPC-2 in C. portucalensis for the first time, delving into plasmid characteristics and transfer mechanisms. Our finding highlights the importance of vigilant monitoring of drug-resistance genes and insertion elements in uncommon strains.Keywords: Citrobacter spp, XDR, blaSFO, blaNDM, blaKPC, IncFII

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