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Updated: Jun 28, 2025
Author Spotlight: Advancing Antibiotic Resistance Research Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System
Published on: January 5, 2024
Exposure to imipenem at sub-minimum inhibitory concentration leads to altered expression of major outer membrane
Srajana Nayak1, Sadanand Dangari Akshay1, Vijaya Kumar Deekshit2
1Nitte (Deemed to be University), Nitte University Centre for Science Education and Research, Department of Bio & Nano Technology, Deralakatte, Mangaluru 575018, India.
Aims:
Acinetobacter baumannii is a nosocomial pathogen known to be multidrug-resistant (MDR), especially to drugs of the carbapenem class. Several factors contribute to resistance, including efflux pumps, β-lactamases, alteration of target sites, and permeability defects. In addition, outer membrane proteins (OMPs), like porins are involved in the passage of antibiotics, and their alteration could lead to resistance development. This study aimed to explore the possible involvement of porins and OMPs in developing carbapenem resistance due to differential expression.
Methods And Results:
The antibiotic-susceptible and MDR isolates of A. baumannii were first studied for differences in their transcriptional levels of OMP expression and OMP profiles. The antibiotic-susceptible isolates were further treated with imipenem, and it was found that the omp genes were differentially expressed. Six of the nine genes studied were upregulated at 1 h of exposure to imipenem. Their expression gradually decreased with time, further confirmed by their OMP profile and two-dimensional gel electrophoresis.
Conclusions:
This study could identify OMPs that were differentially expressed on exposure to imipenem. Hence, this study provides insights into the role of specific OMPs in antibiotic resistance in A. baumannii.
Insights
Outer membrane proteins (OMPs) in Acinetobacter baumannii show differential expression when exposed to carbapenems, contributing to multidrug resistance (MDR). This study identifies specific OMPs involved in carbapenem resistance development.
Area of Science:
- Microbiology
- Molecular Biology
- Infectious Diseases
Background:
- Acinetobacter baumannii is a significant nosocomial pathogen exhibiting multidrug resistance (MDR), particularly to carbapenems.
- Mechanisms of carbapenem resistance include efflux pumps, beta-lactamases, target site alterations, and permeability defects.
- Outer membrane proteins (OMPs), including porins, play a crucial role in antibiotic transport and can be altered to confer resistance.
Purpose of the Study:
- To investigate the potential involvement of outer membrane proteins (OMPs) in the development of carbapenem resistance in Acinetobacter baumannii.
- To explore the role of differential OMP expression in Acinetobacter baumannii's carbapenem resistance.
Main Methods:
- Comparative analysis of transcriptional levels of OMP expression and OMP profiles between antibiotic-susceptible and MDR Acinetobacter baumannii isolates.
- Treatment of antibiotic-susceptible isolates with imipenem to observe changes in OMP gene expression.
- Confirmation of differential expression using OMP profiling and two-dimensional gel electrophoresis.
Main Results:
- Differential expression of OMP genes was observed in Acinetobacter baumannii upon exposure to imipenem.
- Six out of nine studied omp genes were upregulated within 1 hour of imipenem exposure.
- The observed changes in gene expression were corroborated by alterations in the OMP profile.
Conclusions:
- Specific outer membrane proteins (OMPs) are differentially expressed in Acinetobacter baumannii following exposure to carbapenem antibiotics.
- These findings provide valuable insights into the contribution of specific OMPs to antibiotic resistance mechanisms in Acinetobacter baumannii.
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