Horizontal Transfer of Carbapenemase-Encoding Plasmids and Comparison with Hospital Epidemiology Data

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Carbapenemase-producing organisms (CPOs) are a global health threat, causing severe infections.
• Horizontal gene transfer, particularly plasmid-mediated, is a key mechanism for the dissemination of multidrug resistance.
• Understanding the regulation of plasmid conjugation is crucial for controlling the spread of CPOs.

Purpose of the Study:

• To systematically analyze the factors influencing the conjugation efficiency of Klebsiella pneumoniae carbapenemase (blaKPC)-encoding plasmids.
• To investigate the impact of different environmental conditions, plasmid types, and bacterial strains on plasmid transfer.
• To evaluate the predictive power of in vitro models for plasmid mobilization in clinical settings.

Main Methods:

• Utilized an Escherichia coli laboratory strain and clinical isolates as recipients and donors.
• Examined the transfer of four distinct blaKPC-carrying plasmids (pKpQIL, pKPC-47e, pKPC_UVA01, pKPC_UVA02).
• Assessed plasmid transfer frequencies under varying conditions including temperature and substrate, across different donor and recipient pairs.

Main Results:

• Plasmid transfer frequency varied significantly based on donor-recipient pairs, plasmid content, temperature, and substrate.
• Specific plasmids (e.g., pKPC-47e) showed attenuated conjugation efficiency, while others (e.g., pKPC_UVA01) had lower efficiency than pKpQIL.
• Conjugation frequencies in clinical isolates of K. pneumoniae and E. coli showed wide variation without clear correlation to epidemiological data.

Conclusions:

• Multiple variables critically influence blaKPC plasmid conjugation efficiency.
• In vitro experimental models do not reliably predict in vivo plasmid mobilization.
• Further research is needed to identify key factors governing horizontal gene transfer in clinical environments.