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

Published on: May 2, 2018

Nosocomial spread of multi-resistant Klebsiella pneumoniae containing a plasmid encoding multiple beta-lactamases

Ze-Qing Wei1, Ya-Gang Chen1, Yun-Song Yu1

  • 1Infectious Disease Dept, The First Affiliated Hospital, Medical School, Zhejiang University, The Key Laboratory of Infectious Diseases of Public Health Ministry, Zhejiang, Hangzhou, China.

Journal of Medical Microbiology
|August 11, 2005
PubMed

Insights

Six multi-drug resistant Klebsiella pneumoniae isolates from Chinese intensive care units likely originated from a single clone, causing a localized epidemic. This clone carried a transferable 95 kb plasmid encoding multiple beta-lactamase genes, contributing to antibiotic resistance.

Area of Science:

  • Microbiology
  • Genetics
  • Epidemiology

Background:

  • Multi-drug resistant (MDR) Klebsiella pneumoniae poses a significant threat in healthcare settings, particularly in intensive care units (ICUs).
  • Understanding the genetic basis and transmission of antibiotic resistance in clinical isolates is crucial for infection control.

Purpose of the Study:

  • To investigate the genetic characteristics and clonal origin of six MDR Klebsiella pneumoniae isolates from ICUs.
  • To identify the beta-lactamase genes and plasmids responsible for the observed antibiotic resistance.

Main Methods:

  • Plasmid analysis (size, transferability via conjugation)
  • Isoelectric focusing (IEF) of beta-lactamases
  • Restriction enzyme digestion (HindIII) and cloning
  • Polymerase Chain Reaction (PCR) and DNA sequencing
  • Pulsed-field gel electrophoresis (PFGE) for epidemiological typing

Main Results:

  • Six MDR K. pneumoniae isolates shared identical PFGE patterns, suggesting a common origin.
  • A transferable 95 kb plasmid was identified in all isolates.
  • The 95 kb plasmid contained blaDHA-1, ampR, and IS26.
  • Four beta-lactamase genes (blaTEM-1, blaSHV-12, blaCTX-M-3, blaDHA-1) were detected on the 95 kb plasmid.
  • IEF revealed five beta-lactamase activity bands, with distinct inhibition patterns.

Conclusions:

  • The six MDR K. pneumoniae isolates likely represent a single clone responsible for a localized outbreak in the ICUs.
  • The 95 kb plasmid plays a key role in the dissemination of multiple beta-lactamase genes, contributing to the MDR phenotype.

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