Cannabidiol (CBD) and Other Cannabinoids as a Promising Alternative Antibacterial Agent—Pilot Study on Enterococcus faecalis and Enterococcus faecium Clinical Strains

Gram-positive cocci of the Enterococcus genus, despite their prevalence in the environment and the microbiota of healthy people, have become a serious threat in hospitals as opportunistic pathogens. These bacteria have many virulence factors and intrinsic resistance to existing drugs, which significantly narrows the group of effective antimicrobials. Due to the spread of Multi-Drug-Resistant (MDR) strains, there is a need to search for new substances as potential antibiotics. Our work aimed to evaluate the antimicrobial effect of commercially available products (five oils containing cannabidiol (CBD) and its derivatives and one 99% CBD product in the form of crystals) on 20 clinical strains of E. faecalis and E. faecium. We determined the Minimal Inhibitory Concentration (MIC) of CBD oils using the microdilution method in Mueller–Hinton broth (MHB). The CBD displayed antibacterial properties against all tested Enterococcus spp. strains (MIC ≤ 1 μg/mL). The higher concentration of CBD resulted in a larger antibacterial effect. The obtained MICs of pure CBD and CBD crystals were statistically lower (W = 97, p < 0.001) for E. feacium than E. faecalis. This work confirms the antibacterial activity of CBD on Enterococcus spp., providing a solid basis for further research that can help identify new therapeutic options and gain a deeper understanding of the CBD mechanism of action.