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Updated: Dec 27, 2025

Metabolic Profiling to Determine Bactericidal or Bacteriostatic Effects of New Natural Products using Isothermal Microcalorimetry
Published on: October 29, 2020
Cannabidiol is an effective helper compound in combination with bacitracin to kill Gram-positive bacteria
Claes Søndergaard Wassmann1, Peter Højrup2, Janne Kudsk Klitgaard3,4
1Department of Biochemistry and Molecular Biology, Research Unit of Molecular Microbiology, University of Southern Denmark, Odense, Denmark.
Abstract:
The cannabinoid cannabidiol (CBD) is characterised in this study as a helper compound against resistant bacteria. CBD potentiates the effect of bacitracin (BAC) against Gram-positive bacteria (Staphylococcus species, Listeria monocytogenes, and Enterococcus faecalis) but appears ineffective against Gram-negative bacteria. CBD reduced the MIC value of BAC by at least 64-fold and the combination yielded an FIC index of 0.5 or below in most Gram-positive bacteria tested. Morphological changes in S. aureus as a result of the combination of CBD and BAC included several septa formations during cell division along with membrane irregularities. Analysis of the muropeptide composition of treated S. aureus indicated no changes in the cell wall composition. However, CBD and BAC treated bacteria did show a decreased rate of autolysis. The bacteria further showed a decreased membrane potential upon treatment with CBD; yet, they did not show any further decrease upon combination treatment. Noticeably, expression of a major cell division regulator gene, ezrA, was reduced two-fold upon combination treatment emphasising the impact of the combination on cell division. Based on these observations, the combination of CBD and BAC is suggested to be a putative novel treatment in clinical settings for treatment of infections with antibiotic resistant Gram-positive bacteria.
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