ABSTRACT

 The present study was carried out to screen and evaluate antimicrobial activity of leaf extract of Azadirachta indica. Ethanol and aqueous extracts of leaves of A. indica (Neem) were tested against Klebsiella species, Salmonella species, and Staphyloccocus aureus which are known to be resistant to various antibiotics. Neem leaves which were used during this study were collected from Micheal Okpara University of Agriculture, Umudike. The efficiency of the extracts was studied and determined by applying different extract concentrations onto the three test organisms using the agar well dilution method.In this study, the in vitro effect of extracts of Neem (Azadirachta indica) leaves on Kiebsiella species, Salmonella species, and Staphyloccocus aureus were examined respectively. Ethanol and aqueous extracts were prepared from both dry and fresh Neem leaves. The susceptibility of tested bacteria to both extracts was determined by measuring the diameter of inhibition zones formed around agar wells in different agar plates prepared. From the analysis, the results.showed that fresh Neem leaf extracts were found to be the most efficient, showing much inhibitory effect on Kiebsiella species, Salmonella species and Staphylococcus aureus compared to dry leaf extracts. The ethanol extracts were more effective than aqueous extracts in all cases. S. aureus was the bacterium most susceptibly affected by these neem leaf extracts used, while Kiebsiella species and Salmonella species showed lower susceptibility to all the extracts. The results showed that the effectiveness of the extracts was dependent on the concentration used thus the increase in extract concentration increased the inhibition zone