Cannabidiol as a potential anti-biofilm and anti-quorum sensing agent against Escherichia coli O157:H7

Escherichia coli O157:H7 is a major foodborne pathogen capable of forming biofilms and exhibiting increasing resistance to antimicrobials. This growing resistance underscores the need for new strategies, prompting interest in alternative agents such as cannabidiol (CBD), a non-psychoactive cannabis derivative with antimicrobial potential. This study investigated the influence of cannabidiol (CBD) on E. coli O157:H7 in terms of bacterial proliferation, biofilm development, and quorum sensing (QS) activity. CBD's antimicrobial and anti-biofilm properties were determined using the broth microdilution technique and the microtiter plate (MtP) assay, respectively. Additionally, its quorum sensing inhibitory (QSI) capability was assessed by analyzing the reduction in swarming motility at concentrations sub-MIC. The transcriptional profiles of quorum sensing-related genes were quantified using real-time quantitative reverse transcription PCR (RT-qPCR) methodology. MIC and MBC values for CBD ranged from 5 mg/mL to 20 mg/mL, with limited antimicrobial potency compared to ciprofloxacin. The MtP assay revealed that CBD reduced biofilm production of E. coli O157:H7 isolates by up to 50 % and significantly downregulated pfs expression at 20 mg/mL (p < 0.019). The effect of CBD on luxS expression was insignificant (p> 0.05). In conclusion, these findings highlight CBD’s potential as an anti-biofilm and anti-QS agent against E. coli O157:H7.