Evaluation of Antibacterial Activities of Tanzanian Moringa oleifera Extracts against Escherichia coli and Klebsiella pneumonia Clinical Isolates

Abstract

In vitro antibacterial activities of methanolic leaf and seed extracts of Moringa oleifera grown in Dodoma, Tanzania were evaluated using standard microdilution and disc diffusion methods against extended spectrum beta lactamase producing Gram negative bacteria (Escherichia coli and Klebsiella pneumoniae). Microdilution method showed no activity at concentration of 20 mg/mL for all the extracts except leaf extract which exhibited minimum inhibition at concentration of  2.5 µg/mL for E. Coli but when high concentrations of the extracts were used in the disc diffusion method then the results exhibited the highest killing susceptibility at concentration of 0.4 g/mL with zone of inhibition 31 mm for leaf extract and 26 mm for seed extract against E. coli, and 27 mm for leaf extract and 29 mm for seed extract against K. pneumonia. Additionally, when both extracts were screened qualitatively for phytoconstituents using standard methods, leaf extract confirmed the presence of carbohydrates, cardiac glycosides,  tannins and quinones, and seed extract confirmed the presence of proteins, carbohydrates, cardiac glycosides, alkaloids, terpenoids and quinones. These phytoconstituents can be new sources of future antibiotics that potentially combat the existing problem of antimicrobial resistance and thus, creating an awareness in the community regarding the usage of M. oleifera growing widely but neglected in Tanzania in spite of its nutritional values and traditional uses. Keywords: Moringa oleifera; Phytoconstituents; Antibacterial activity; Escherichia coli and Klebsiella pneumoniae