Antibacterial Potential of Aqueous Extracts of Ivorian Medicinal Plants against Multidrug-Resistant Clinical Isolates and Wild Strains

Medicinal plants represent an effective alternative in the fight against common and neglected bacterial diseases in Africa, particularly in Côte d'Ivoire. However, they are subject to anthropogenic pressure that can lead to the disappearance of many of them, creating an imbalance in plant biodiversity. The objective of this study is to evaluate the antibacterial activity of aqueous extracts of nine (9) medicinal plants from the Ivorian flora against Gram-negative bacteria (Salmonella typhimurium, Pseudomonas aeruginosa), Gram-positive bacteria (Staphylococcus aureus), and enterobacteria (Shigella sp., Escherichia coli, and Proteus mirabilis). These bacteria include wild-type and multidrug-resistant strains. Nine aqueous extracts from the organs of nine plant species belonging to nine botanical families were prepared for testing. Based on their activity against the bacteria, the extract of Terminalia leiocarpa (DC) Guill. & Perr. (Combretaceae) was selected to determine the antibacterial parameters (MIC and MBC) using the diffusion method in agar (solid) and macrodilution in liquid. The largest inhibition zone diameter (24 ± 1 mm) was obtained with the extract of this plant at a concentration of 50 mg/mL. This extract also yielded the best MIC (0.39 ± 0.0 mg/mL) and MBC (0.39 ± 0.0 mg/mL), which were identical. Furthermore, phytochemical sorting performed on all plant organs using thin-layer chromatography detected the presence of several phytoconstituents, including saponins, tannins, flavonoids, polyphenols, alkaloids, and sesquiterpenes, which are likely responsible for the observed activity. This research supports the traditional use of these plants in the treatment of bacterial infections, a significant public health issue.