Hospital Universitario Ramon y Cajal (IRYCIS) and CIBERESP 1 article published in JoVE Genetics Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance Jose Antonio Escudero1,2, R Craig MacLean3, Alvaro San Millan4 1Department of Animal Health, Universidad Complutense de Madrid, 2Visavet Health Surveillance Centre, Universidad Complutense de Madrid, 3Department of Zoology, University of Oxford, 4Department of Microbiology, Hospital Universitario Ramon y Cajal (IRYCIS) and CIBERESP Here we present an experimental method to test the role of multicopy plasmids in the evolution of antibiotic resistance.