Developing a framework for tracking antimicrobial resistance gene movement in a persistent environmental reservoir

Area of Science:

• Microbiology
• Genomics
• Epidemiology

Background:

• Mobile genetic elements, such as plasmids, are critical drivers of antibiotic resistance.
• The carbapenemase gene blaKPC is a significant threat in healthcare settings, contributing to carbapenem resistance.

Purpose of the Study:

• To reconstruct bacterial genomes and plasmids to understand the evolution and movement of the blaKPC gene over five years in hospital drains.
• To develop and validate a novel mathematical approach for assessing the directional movement of antimicrobial resistance genes.

Main Methods:

• Complete bacterial genome and plasmid assemblies were reconstructed from 82 isolates collected over five years.
• A novel mathematical approach, the 'Composite-Sample Complex', was developed to model the directional movement of antimicrobial resistance genes, considering both plasmid and chromosomal DNA.
• The model was validated to identify gene donors and recipients and assess transposition events.

Main Results:

• 14 unique strains from 10 species carrying blaKPC were identified, associated with 113 plasmids across 16 replicon types.
• The Composite-Sample Complex model demonstrated frequent transposition of blaKPC between plasmids and integration into the bacterial chromosome within specific hospital drains.
• The study highlights the dynamic nature of antimicrobial resistance gene mobilization in a confined environment.

Conclusions:

• Mobile genetic elements, particularly plasmids, facilitate the rapid dissemination of critical antibiotic resistance genes like blaKPC.
• The Composite-Sample Complex provides a robust framework for understanding the complex dynamics of antimicrobial resistance gene transfer.
• This research offers insights into the evolution and spread of antibiotic resistance in hospital environments, informing infection control strategies.