Evaluation of the Antibacterial Activity of Terminalia leiocarpa (DC) Baill. (Combretaceae) Leaves on the in vitro Growth of Enterobacteriaceae Strains Producing Extended-spectrum Beta-lactamase and Phytochemical Screening

Abstract

Extended-spectrum beta-lactamase-producing bacteria are the root cause of therapeutic failures observed in the treatment of bacterial infections. This study aimed to evaluate the antibacterial effects of methanolic and aqueous extracts of Terminalia leiocarpa (DC) Baill. (Combretaceae) leaves, a plant prized in Ivorian traditional medicine, against ten clinical strains of extended-spectrum beta-lactamase-producing Enterobacteriaceae and a reference strain. The antibacterial activity was studied using the agar diffusion method (solid) in wells and the liquid macrodilution method. For phytochemical screening, the thin-layer chromatography (TLC) characterization method was used. In this study, both aqueous and alcoholic extracts were active to varying degrees. The largest inhibition diameter (32 ± 0.2 mm) was obtained with the aqueous extract on Shigella flexneri 392PI21 at a concentration of 50 mg/ml. This extract exerted bactericidal activity on all strains with MICs ranging from 0.156 to 0.312 mg/ml, while the methanolic extract was bactericidal on the majority of strains with MICs ranging from 0.078 mg/ml to 1.25 mg/ml. Furthermore, phytochemical screening revealed a wealth of secondary metabolites such as saponins, tannins, flavonoids, polyterpenes, anthocyanins, polyphenols that can be beneficial in the management of many enterobacteriaceae pathologies. This work justified the traditional use of Terminalia leiocarpa (DC) Baill in the treatment of various enterobacteriaceae-related infections.