Potentiation of Antibacterial Activity of Cefixime in Synergy with Cirsium arvense (L.) Scop. Against Resistant Bacterial Isolates

Antibiotic resistance is a major health priority, with the concern over antibiotic resistance growing. The rise in antibiotic-resistant bacteria coupled with the limited new therapeutics puts pressure on community and hospital healthcare systems and leads to excessive morbidity and mortality. Given this, there has been significant interest into potential new and/or combination antibacterial treatments including certain plant extracts. When combined with resistance medicines, these extracts can re-sensitize their potency. One such plant is Cirsium arvense which has been traditionally used for its anti-inflammatory and antimicrobial properties. Preliminary findings suggest that its extracts may enhance the activity of conventional antibiotics against resistant strains like MRSA. The current study assessed cefixime’s and Cirsium arvense extracts’ synergistic antibacterial efficacy against Escherichia coli, Acinetobacter baumannii, and methicillin-resistant Staphylococcus aureus (MRSA). The antibacterial activity of extracts and the susceptibility profile of antibiotics were assessed using the disc diffusion and microbroth dilution assays. Chequerboard, time-kill kinetics, and protein content tests were performed to verify synergistic antibacterial effect. Our results demonstrated that when these extracts were applied to clinical strains of bacteria along with the cefixime, there was complete or partial synergy was displayed. Time-kill kinetics demonstrated that synergism was dependent on both concentration and time, and bacterial isolates treated with these exhibited significantly reduced bacterial growth and protein content. Taken together, these results show that Cirsium arvense extracts enhance the efficacy of conventional antibiotics against antibiotic-resistant strains of Escherichia coli, Acinetobacter baumannii, and MRSA and clearly suggest that these plant extracts could be used as additives to current resistant antibiotics for the future management or treatment of resistant bacterial infections.