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Updated: May 18, 2026

Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance
Published on: May 2, 2018
Genotypic and phenotypic evaluation of the evolution of high-level daptomycin nonsusceptibility in
Romney M Humphries1, Theodoros Kelesidis, Ryan Tewhey
1Department of Pathology & Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA. rhumphries@mednet.ucla.edu
Abstract:
Whole-genome sequencing and cell membrane studies of three clonal Enterococcus faecium strains with daptomycin MICs of 4, 32, and 192 μg/ml were performed, revealing nonsynonymous single nucleotide variants in eight open reading frames, including those predicted to encode a phosphoenolpyruvate-dependent, mannose-specific phosphotransferase system, cardiolipin synthetase, and EzrA. Membrane studies revealed a higher net surface charge among the daptomycin-nonsusceptible isolates and increased septum formation in the isolate with a daptomycin MIC of 192 μg/ml.
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