Related Experiment Video

Updated: Jul 10, 2026

Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung
09:26

Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung

Published on: January 22, 2021

Preferential selection of IMP and VIM metallo-beta-lactamases by imipenem in Pseudomonas aeruginosa

Fiona Walsh1, Simon Bracher, Phil Turner

  • 1University of Edinburgh, Edinburgh, UK.

Chemotherapy
|October 16, 2007
PubMed

Insights

Exposure to imipenem rapidly induced carbapenem resistance in mixed Pseudomonas aeruginosa populations. However, meropenem exposure only selected for resistance in strains harboring VIM beta-lactamases.

Area of Science:

  • Microbiology
  • Antimicrobial Resistance
  • Molecular Biology

Background:

  • Pseudomonas aeruginosa is an opportunistic pathogen.
  • Carbapenem resistance is a growing global health threat.
  • Beta-lactamases, such as IMP and VIM, are key mechanisms of carbapenem resistance.

Purpose of the Study:

  • To investigate the emergence of carbapenem resistance in mixed Pseudomonas aeruginosa populations.
  • To compare the effects of imipenem and meropenem exposure on resistance development.

Main Methods:

  • Culturing mixed populations of carbapenem-susceptible and resistant Pseudomonas aeruginosa strains.
  • Exposure to imipenem and meropenem.
  • Assessing resistance profiles to both carbapenems.

Main Results:

  • Exposure to imipenem led to the development of resistance to both imipenem and meropenem in mixed populations, irrespective of the beta-lactamase type (IMP or VIM).
  • Exposure to meropenem resulted in cross-resistance to both carbapenems only in mixed populations containing the VIM beta-lactamase-producing strains.

Conclusions:

  • Imipenem is a potent selective agent for carbapenem resistance in mixed Pseudomonas aeruginosa populations.
  • The type of beta-lactamase present influences the development of cross-resistance to other carbapenems.

Related Concept Videos

Mechanism of Antibiotic Resistance in MRSA01:25

Mechanism of Antibiotic Resistance in MRSA

Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...
Clinical Significance of Antibiotic Resistance01:25

Clinical Significance of Antibiotic Resistance

Methicillin-resistant Staphylococcus aureus (MRSA) presents a critical public health threat, arising from its capacity to resist β-lactam antibiotics due to acquisition of the mecA gene within the staphylococcal cassette chromosome mec (SCCmec). This gene encodes penicillin-binding protein 2a (PBP2a), which impairs binding efficacy of methicillin and other β-lactams. MRSA has evolved into distinct clonal lineages impacting humans and animals alike, reinforcing its significance within the One...
Antibiotic Selection00:57

Antibiotic Selection

Overview
Inhibitors of Gram-positive Cell Wall Synthesis01:23

Inhibitors of Gram-positive Cell Wall Synthesis

Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...
Development of Antibiotic Resistance01:30

Development of Antibiotic Resistance

Antibiotic resistance is a major public health concern that arises when bacteria evolve mechanisms to withstand the effects of antibiotic treatments. This resistance can be intrinsic, acquired through genetic mutations, or transferred between bacteria via horizontal gene transfer. The development of antibiotic resistance poses significant challenges in treating bacterial infections and necessitates ongoing research to develop new therapeutic strategies.Intrinsic resistance occurs when bacterial...
Antimicrobial Proteins01:23

Antimicrobial Proteins

Antimicrobial proteins are important components of the immune system. They aid the body in combating pathogens by either killing them directly or hindering their replication processes. Four main types of antimicrobial substances are interferons, the complement system, iron-binding proteins, and antimicrobial proteins.
Interferons
Interferons (IFNs) are proteins produced by lymphocytes, macrophages, and fibroblasts infected with viruses. While IFNs cannot prevent viruses from entering and...