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Emergence of OXA-484-Producing Klebsiella variicola in China
Haoyu Ge1,2, Jie Qiao1,2, Hao Xu2
1Department of Laboratory Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China.
Purpose:
The frequent and inappropriate use of antibiotics has caused a dramatic rise in the number, species, and degree of multi-drug resistant bacteria, making them more prevalent and difficult to treat. In this context, the aim of the present study was to characterize the OXA-484-producing strains isolated from a perianal swab of a patient by using whole-genome analysis.
Patients And Methods:
In this study, carbapenemase-producing Klebsiella variicola was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), average nucleotide identity (ANI) and PCR. S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and Southern blotting were utilized to characterize the plasmid profiles of K. variicola 4717. In particular, WGS was performed to obtain genomic information on this clinical isolate, and assemble all the plasmids of the bla OXA-484-harboring strain.
Results:
The antimicrobial susceptibility pattern of K. variicola 4717 revealed that it was resistant to a range of antibiotics, including aztreonam, imipenem, meropenem, ceftriaxone, cefotaxime, ceftazidime, levofloxacin, ciprofloxacin, piperacillin-tazobactam, methylene-sulfamer oxazole, amoxicillin-clavulanic acid, cefepime, and tigecycline. Its susceptibility to chloromycin was intermediate, while it was still susceptible to amikacin, gentamicin, fosfomycin, and polymyxin B. The presence of two companion plasmids, p4717_1 and p4717_2, together with a plasmid carrying the bla OXA-484 gene was observed. An in-depth investigation of p4717-OXA-484 uncovered that it is an IncX3-type plasmid and shares a similar segment encoded by IS26. Given the similar genetic background, it was conceivable that bla OXA-484 could have developed from bla OXA-181 through a series of mutations.
Conclusion:
Herein, we described the first genome sequence of K. variicola strain harbouring the class D β-actamase bla OXA-484 in an Inc-X3-type plasmid. Our work also uncovered the genetic characterization of K. variicola 4717 and the importance of initiating antimicrobial detection promptly.
Insights
Multi-drug resistant bacteria pose a significant threat. This study details the first genome sequence of OXA-484-producing Klebsiella variicola, a carbapenemase-resistant strain, highlighting the need for prompt antimicrobial detection.
Area of Science:
- Microbiology
- Genomics
- Antimicrobial Resistance
Background:
- Antibiotic misuse has led to a rise in multi-drug resistant bacteria, complicating treatment options.
- Carbapenemase-producing Enterobacteriaceae are a growing global health concern.
Purpose of the Study:
- To characterize OXA-484-producing Klebsiella variicola strains using whole-genome analysis.
- To investigate the genetic basis of carbapenem resistance in a clinical isolate.
Main Methods:
- Identification of Klebsiella variicola using MALDI-TOF MS, ANI, and PCR.
- Plasmid profiling via S1-PFGE and Southern blotting.
- Whole-genome sequencing (WGS) for comprehensive genomic and plasmid information.
Main Results:
- Klebsiella variicola 4717 exhibited resistance to numerous antibiotics, including carbapenems.
- The strain harbored the blaOXA-484 gene on an IncX3-type plasmid, designated p4717-OXA-484.
- The blaOXA-484 gene likely evolved from blaOXA-181 through mutations within a similar genetic context.
Conclusions:
- This study presents the first genome sequence of a Klebsiella variicola strain carrying blaOXA-484 on an IncX3 plasmid.
- The findings underscore the importance of rapid antimicrobial susceptibility testing and genomic surveillance for emerging resistance mechanisms.
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