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Updated: May 5, 2026
Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance
Published on: May 2, 2018
Single origin of three plasmids bearing blaCTX-M-15 from different Klebsiella pneumoniae clones
1Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea.
Objectives:
To determine and compare the complete nucleotide sequences of plasmids carrying blaCTX-M-15 from three different Klebsiella pneumoniae clones.
Methods:
IncFII-type plasmids pKP02022, pKP09085 and pKP007 were extracted from three K. pneumoniae strains. These strains belong to sequence types (STs) ST15, ST48 and ST23, respectively, and were isolated in Korea. Plasmids were sequenced using the 454 Genome Sequencer FLX system.
Results:
The three plasmids, pKP02022 (203577 bp), pKP09085 (213019 bp) and pKP007 (246 176 bp), all exhibited a very similar structure, with a pKPN3-like backbone and a resistance region including blaOXA-1, aac(6')-Ib-cr and cat genes as well as blaCTX-M-15. They were also very similar to pUUH239.2, previously isolated in Sweden. Iron (III) uptake-related genes were found in pKP007 from the ST23 strain, which has been reported to be associated with liver abscesses. The resistance region contained several insertion sequences, such as IS26, which may play an important role in structural rearrangements of plasmids.
Conclusions:
The very similar structure of the three plasmids, extracted from different clones, suggests that the spread of CTX-M-producing K. pneumoniae isolates might result from the horizontal transfer of plasmids and subsequent integration and recombination.
Insights
The complete nucleotide sequences of three Klebsiella pneumoniae plasmids carrying blaCTX-M-15 were determined. These plasmids share a similar structure, suggesting horizontal gene transfer drives the spread of antibiotic resistance.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Klebsiella pneumoniae is a significant opportunistic pathogen.
- The blaCTX-M-15 gene confers resistance to extended-spectrum cephalosporins.
- Plasmids are key vectors for antibiotic resistance gene dissemination.
Purpose of the Study:
- To determine and compare the complete nucleotide sequences of plasmids harboring the blaCTX-M-15 gene.
- To investigate the genetic context and structural features of these plasmids.
- To understand the molecular mechanisms underlying the spread of CTX-M-producing K. pneumoniae.
Main Methods:
- Extraction of IncFII-type plasmids from three K. pneumoniae strains (ST15, ST48, ST23) isolated in Korea.
- Sequencing of plasmids using the 454 Genome Sequencer FLX system.
- Comparative analysis of plasmid structures and genetic elements.
Main Results:
- Three plasmids (pKP02022, pKP09085, pKP007) exhibited highly similar structures with a pKPN3-like backbone.
- A common resistance region included blaOXA-1, aac(6')-Ib-cr, cat, and blaCTX-M-15 genes.
- Insertion sequences like IS26 were identified, potentially facilitating plasmid rearrangements. Iron uptake genes were noted in one plasmid associated with liver abscesses.
Conclusions:
- The structural similarity of plasmids from diverse K. pneumoniae clones suggests horizontal plasmid transfer.
- This horizontal transfer, followed by integration and recombination, likely drives the dissemination of CTX-M-producing K. pneumoniae.
- Understanding plasmid dynamics is crucial for combating antibiotic resistance.
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