Antimicrobial resistance determinants in silage

Area of Science:

• Microbiology
• Genetics
• Food Science

Background:

• Antimicrobial resistance (AMR) is a growing global health concern.
• Animal products can contribute to AMR development and spread through antibiotic residues and resistant bacteria.
• Fermented foods have shown significant antimicrobial resistance gene (ARG) content, suggesting similar risks in animal feed.

Purpose of the Study:

• To identify the types of ARGs present in silage.
• To determine the mobility characteristics of ARGs found in silage.
• To assess silage as a potential source of ARGs in the food chain.

Main Methods:

• Bioinformatic analysis of 52 publicly available deep-sequenced silage samples.
• Shotgun metagenome next-generation sequencing was employed.
• Identification and characterization of antimicrobial resistance genes (ARGs) and their mobile genetic elements.

Main Results:

• A total of 16 distinct ARGs were identified, occurring 54 times across the analyzed silage samples.
• More than 50% of the detected ARGs were found to be mobile.
• Mobility was linked to integrative mobile genetic elements, prophages, and plasmids.

Conclusions:

• Silage represents a significant and previously underestimated reservoir of ARGs.
• The high mobility of ARGs in silage indicates a substantial risk for their dissemination within the food chain.
• Further research is needed to mitigate ARG transmission from animal feed to the wider environment and human population.