Copper induced augmentation of antibiotic resistance in Acinetobacter baumannii MCC 3114
Ravi Chauhan1, Hardi Patel1, Bhavna Bhardwaj1
1Microbiology Lab, School of Life Sciences, Central University of Gujarat, Gandhinagar, Gujarat, 382030, India.
Abstract:
Increasing antibiotic resistance among the common nosocomial pathogen i.e. Acinetobacter baumannii poses life threat to the health care workers as well as to the society. The dissemination of antibiotic resistance in this pathogen at an alarming rate could be not only due to the overuse of antibiotics but also due to the stress caused by exposure of bacterium to several environmental contaminants in their niches. In the present study, effect of copper stress on augmentation in the antibiotic resistance of A. baumannii MCC 3114 against three clinically used antibiotics was investigated along with the phenotypic and genotypic alterations in the cell. It induced 8, 44 and 22-fold increase in resistance against colistin, ciprofloxacin and levofloxacin, respectively. Moreover, the biofilm formation of adapted culture was significantly enhanced due to a dense EPS around the cell (as revealed by SEM images). The structural changes in EPS were demonstrated by FTIR spectroscopy. The adequate growth of adapted MCC 3114 despite increased level of ROS indicates its persistence in copper and ROS stress. The physiological alterations in cell viz., increased efflux pump activity and decreased membrane permeability was observed. Molecular analysis revealed increased expression of efflux pump related genes, oxidative stress genes, integron and antibiotic resistance genes. In sum, our study revealed that the exposure of the critical pathogen, A. baunmannii to copper in hospital settings and environmental reservoirs can impose adaptive pressure which may lead to genotypic as well phenotypic changes in cell resulting into the augmentation of antibiotic resistance.
Insights
Copper exposure significantly increases antibiotic resistance in Acinetobacter baumannii, a common hospital pathogen. This environmental stress enhances bacterial survival and promotes the spread of antimicrobial resistance.
Area of Science:
- Environmental Microbiology
- Antimicrobial Resistance
- Bacterial Pathogenesis
Background:
- Acinetobacter baumannii is a critical nosocomial pathogen with increasing antibiotic resistance.
- Environmental contaminants, such as copper, may contribute to the dissemination of antimicrobial resistance.
- Understanding the impact of environmental stressors on A. baumannii is crucial for public health.
Purpose of the Study:
- To investigate the effect of copper stress on antibiotic resistance in A. baumannii.
- To analyze phenotypic and genotypic alterations in copper-stressed A. baumannii.
- To explore the role of environmental factors in the augmentation of antimicrobial resistance.
Main Methods:
- Exposure of A. baumannii MCC 3114 to copper stress.
- Determination of antibiotic resistance levels against colistin, ciprofloxacin, and levofloxacin.
- Scanning Electron Microscopy (SEM) for biofilm and Extracellular Polymeric Substance (EPS) analysis.
- Fourier-Transform Infrared (FTIR) spectroscopy for EPS structural changes.
- Assessment of reactive oxygen species (ROS) tolerance, efflux pump activity, and membrane permeability.
- Molecular analysis of gene expression (efflux pump, oxidative stress, integron, and antibiotic resistance genes).
Main Results:
- Copper stress induced significant increases in resistance: 8-fold for colistin, 44-fold for ciprofloxacin, and 22-fold for levofloxacin.
- Adapted A. baumannii exhibited enhanced biofilm formation with denser EPS, altered structural properties, and increased ROS tolerance.
- Physiological changes included increased efflux pump activity and decreased membrane permeability.
- Molecular analysis revealed upregulated expression of genes related to efflux pumps, oxidative stress, integrons, and antibiotic resistance.
Conclusions:
- Copper exposure acts as an adaptive pressure, leading to augmented antibiotic resistance in A. baumannii.
- Environmental copper in hospital settings and reservoirs can drive genotypic and phenotypic changes, exacerbating the antimicrobial resistance crisis.
- This study highlights the link between environmental contaminants and the evolution of antibiotic-resistant pathogens.
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