Antibacterial Activity of Azadirachta indica Leaf Extracts Against Clinical Isolates of Klebsiella pneumoniae and Staphylococcus aureus

Abstract

The increasing prevalence of antibiotic-resistant bacterial pathogens has necessitated the search for alternative antimicrobial agents from natural sources. This study investigated the phytochemical constituents and antibacterial activity of crude leaf extracts of Azadirachta indica against Staphylococcus aureus and Klebsiella pneumoniae. Fresh A. indica (neem) leaves were collected, authenticated, air-dried, and pulverized before extraction using ethanol and distilled water. Standard qualitative phytochemical screening methods were used to identify the presence of Phytochemical constituents. Antibacterial activity was evaluated using the agar well diffusion method, while Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined using broth dilution techniques. The results revealed the presence of flavonoids, steroids, tannins, alkaloids, saponins, terpenoids, glycosides, and phenolics compounds in both extracts, with higher concentrations observed in the ethanolic extract. Both extracts demonstrated antibacterial activity against the test organisms, with the ethanolic extract showing larger zones of inhibition ranging from 12.5 ± 0.4 to 25.1 ± 0.5 and lower MIC and MBC values compared to the aqueous extract. The findings confirm the antibacterial potential of Azadirachta indica leaves and support their traditional use in the management of bacterial infections. The study highlights the potential of A. indica leaf extracts as alternative antimicrobial agents against Klebsiella pneumonniae and Staphylococcus aureus.