PhD Thesis defense by Cristina Bernabé Balas at the VISAVET Centre of the Complutense University of Madrid

October 21^st, 2019

During the recent years, the levels of antimicrobial resistance have been drastically increasing. This increase is exacerbated by the misuse of antibiotics since they were introduced into clinical practice, which has facilitated the selection of multiresistant bacteria and their dissemination in microbial environments.Plasmids play a fundamental role in the dissemination of antibiotic resistance, as they can be transmitted horizontally among bacterial populations, leading to the spread of the resistance genes they harbor. However, when a bacterium acquires a new plasmid, the replication and translation of the genes encoded in the plasmid can produce a biological cost to the bacterium, which generates a growth deceleration and lower competitiveness against plasmid-free bacteria. In environments where there is no selective pressure, this could result in the loss of the plasmid in the bacterial population. The biological cost imposed by plasmids can be compensated by adaptive evolution, which allows the adaptation of plasmids to novel hosts and facilitates their persistence in the population. Nevertheless, most adaptive mechanisms described in literature are exclusively on conjugative plasmids and cannot be applied to small non-conjugative plasmids...

Related link: Identificación y caracterización molecular de mecanismos de adaptación plasmídica a nuevas familias bacterianas