Objectives: To determine the fitness effects of various mobile genetic elements (MGEs) in Enterococcus faecium and Enterococcus faecalis when newly acquired. We also tested the hypothesis that the biological cost of vancomycin resistance plasmids could be mitigated during continuous growth in the laboratory.<p> <p>Methods: Different MGEs, including two conjugative transposons (CTns) of the Tn916 ...