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Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance
09:00

Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance

Published on: May 2, 2018

[Study on the genetic structure and transmission mechanism of a plasmid-mediated AmpC beta-lactamase]

Wei-xin Lu1, Ze-qing Wei, Yun-song Yu

  • 1Infectious Disease Dept, 1st Affiliated Hospital, Medical School, Zhejiang University, Key Lab of Infectious Diseases of Public Health Ministry, Zhejiang Hangzhou 310003, China.

Zhonghua Yi Xue Za Zhi
|December 6, 2005
PubMed
Abstract

Insights

This study cloned the plasmid-mediated AmpC beta-lactamase gene, bla(DHA-1), from Klebsiella pneumoniae. The IS26 insertion sequence may facilitate the gene

Area of Science:

  • Molecular Biology
  • Microbiology
  • Genetics

Background:

  • Multiple-drug resistance in Klebsiella pneumoniae is a growing public health concern.
  • Plasmid-mediated AmpC beta-lactamases contribute significantly to resistance against cephalosporins.
  • Understanding the genetic basis and transmission of these resistance genes is crucial.

Purpose of the Study:

  • To clone the plasmid-mediated AmpC beta-lactamase gene from a multidrug-resistant Klebsiella pneumoniae isolate.
  • To characterize the cloned gene and its surrounding genetic elements.
  • To elucidate the mechanism of transmission for this resistance determinant.

Main Methods:

  • Plasmid DNA extraction and restriction digestion.
  • Ligation of fragments into pGEM-T Easy vector and transformation into E. coli DH5alpha.
  • Sequencing by primer walking, MIC determination, and isoelectric focusing electrophoresis (IFE).

Main Results:

  • A 5.2-kb insert containing bla(DHA-1) and ampR was cloned into the recombinant plasmid pT948.
  • The bla(DHA-1) gene was found adjacent to insertion sequence IS26 and an integron.
  • The recombinant expressed a beta-lactamase with a pI of 7.7, conferring resistance to cefoxitin and inducible resistance to ceftazidime.

Conclusions:

  • The cloned plasmid-mediated ampC gene was identified as bla(DHA-1).
  • The presence of IS26 flanking bla(DHA-1) suggests a role in its translocation from the chromosome to plasmids.
  • This finding provides insight into the genetic mechanisms driving the spread of AmpC beta-lactamase resistance.

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