Antibacterial activity of Moringa oleifera leaves extract against vancomycin resistant Enterococcus faecalis Clinical Isolates

Abstract

Vancomycin-resistant Enterococcus faecalis (VRE) is a high-priority pathogen 
associated with limited therapeutic options, necessitating the exploration of 
alternative antimicrobial agents. Medicinal plants represent promising candidates 
because of their diverse bioactive constituents and potential multi-target 
mechanisms. This study evaluated the antibacterial activity of ethanolic Moringa 
oleifera leaf extract against clinical isolates of vancomycin-resistant E. faecalis. 
Clinical isolates were phenotypically identified using Gram staining and standard 
biochemical tests, while vancomycin resistance was determined by the disk diffusion 
method. Ethanolic leaf extract of M. oleifera was prepared and evaluated for 
antibacterial activity using agar well diffusion, broth microdilution for minimum 
inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) 
assays. Qualitative phytochemical screening of the extract was also performed. All 
three phenotypically confirmed E. faecalis isolates (100%) exhibited resistance to 
vancomycin, with inhibition zones ≤14 mm. Phytochemical analysis revealed the 
presence of alkaloids, flavonoids, tannins, saponins, and steroids. The extract 
demonstrated concentration-dependent antibacterial activity, with inhibition zones 
increasing from 9–11 mm at 25 mg/mL to 20–24 mm at 200 mg/mL. The MIC and MBC 
were 6.25 mg/mL and 12.5 mg/mL, respectively, yielding an MBC/MIC ratio of 2.0 
and indicating bactericidal activity. However, molecular confirmation of vancomycin
resistance genes was not achieved. These findings demonstrate that M. oleifera leaf 
extract possesses bactericidal activity against phenotypically confirmed VRE 
isolates and may represent a potential source of alternative antimicrobial agents. 
Further studies involving bioactive-compound isolation, antimicrobial synergy, 
molecular characterization, and in vivo efficacy are warranted.