The Role of Integrative and Conjugative Elements in Antibiotic Resistance Evolution.

Mobile genetic elements (MGEs), such as plasmids and integrative and conjugative elements (ICEs), are main drivers for the spread of antibiotic resistance (AR). Coevolution between bacteria and plasmids shapes the transfer and stability of plasmids across bacteria. Although ICEs outnumber conjugative plasmids, the dynamics of ICE-bacterium coevolution, ICE transfer rates, and fitness costs are as yet largely unexplored. Conjugative plasmids and ICEs are both transferred by type IV secretion systems, but ICEs are typically immune to segregational loss, suggesting that the evolution of ICE-bacterium associations varies from that of plasmid-bacterium associations. Considering the high abundance of ICEs among bacteria, ICE-bacterium dynamics represent a promising challenge for future research that will enhance our understanding of AR spread in human pathogens.