Combating Multidrug Resistance: A Synergistic Approach Using Medicinal Plant Extracts

Abstract

The emergence and rapid spread of multidrug-resistant (MDR) bacterial pathogens have necessitated the search for alternative antimicrobial agents, particularly from natural sources. This study investigates the synergistic antibacterial activity of three ethnomedicinal plants, Lantana camara (LC) and Cissampelos pareira (CP), Parthenium hysterophorus (CG) against clinically relevant MDR isolates. A total of four MDR strains (BI4 (Pseudomonas aeruginosa), BT3 (Bacillus. pumilus), HMR2 (Cellulosiumicrobium. cellulan), and TD7 (Pseudomonas aeruginosa)), previously isolated from soil samples in hospital-associated environments, and were selected for in vitro antimicrobial screening. Combinatorial extracts of LC and CP (LC + CP) were prepared and evaluated for their antibacterial efficacy using the agar well diffusion method. The LC + CP combination exhibited the highest overall activity with inhibition zones ranging from 16.17 ± 0.27 mm to 24.17 ± 0.27 mm. Based on this preliminary finding, the extract was further assessed for its Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) through broth dilution and agar plating methods, respectively. MIC values ranged from 1.562 to 6.25 mg/ml, while MBC values varied between 3.125 and 12.5 mg/ml. The most notable effect was observed against TD7, which exhibited the lowest MIC and MBC values, indicating high sensitivity to the plant extract combination. MBC/MIC ratios ≤4 across all isolates confirmed the bactericidal nature of the combination. The observed efficacy may be attributed to the synergistic action of phytoconstituents such as flavonoids, alkaloids, and terpenoids. These findings highlight the potential of LC + CP as a promising plant-based antimicrobial strategy against MDR pathogens and warrant further investigation into its phytochemical composition and in vivo efficacy.