Different genetic supports for the tet(S) gene in Enterococci

Area of Science:

• Microbiology
• Genetics
• Antimicrobial Resistance

Background:

• Enterococci are significant opportunistic pathogens.
• The tet(S) gene confers tetracycline resistance.
• Understanding the genetic context of resistance genes is crucial for tracking their spread.

Purpose of the Study:

• To investigate the genetic diversity of tet(S) gene contexts in enterococci.
• To determine the geographical and host distribution of these contexts.
• To elucidate the evolutionary origins of tet(S)-carrying genetic elements.

Main Methods:

• Analysis of 13 enterococcal isolates from human, animal, and environmental sources.
• Molecular characterization of tet(S) gene loci.
• Comparative genomics using GenBank database.

Main Results:

• Identified two main tet(S) genetic contexts: chromosomal CTn6000 variants and plasmid-borne composite platforms.
• Composite platforms were flanked by IS1216 and ranged from 40 to 115 kb.
• Geographical and host diversity of tet(S) contexts was observed.

Conclusions:

• CTn6000 variants are likely the evolutionary origin of diverse tet(S)-harboring platforms.
• These platforms have been mobilized to various plasmids.
• This highlights the dynamic nature of antimicrobial resistance gene dissemination.