Detection and Quantification of Conjugative Transfer of Mobile Genetic Elements Carrying Antibiotic Resistance Genes

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Multidrug resistance is a growing concern in the zoonotic pathogen Streptococcus suis.
• Antimicrobial resistance genes are often located on chromosomal Mobile Genetic Elements (MGEs), including Integrative and Conjugative Elements (ICEs) and Integrative and Mobilizable Elements (IMEs).
• Complex arrangements of MGEs, such as tandems or nested composite elements, hinder their identification.

Purpose of the Study:

• To investigate the mobility of MGEs carrying antimicrobial resistance genes in Streptococcus suis.
• To establish methods for evaluating the transfer and spread of resistance genes via MGEs.

Main Methods:

• Selection of appropriate donor-recipient bacterial pairs for mating assays.
• Performing PCR-based excision tests to confirm the circularization of genetic elements.
• Conducting conjugation assays to quantify the transfer of MGEs between strains.

Main Results:

• Demonstrated the ability of MGEs to excise from the Streptococcus suis chromosome.
• Successfully evaluated the conjugative transfer of MGEs between strains.
• Identified complex MGE structures that complicate analysis.

Conclusions:

• MGEs, particularly ICEs and IMEs, play a significant role in the dissemination of antimicrobial resistance genes within and between Streptococcus suis populations.
• Understanding MGE mobility is essential for controlling the spread of resistance in a One Health context.
• Standardized methods for assessing MGE mobility are critical for surveillance and intervention strategies.