Assessment of antibacterial activity of Neem plant (Azadirachta indica) on Staphylococcus aureus and Escherichia coli

Abstract

The present study was carried out to screen and evaluate antimicrobial activity of leaf and bark extracts of Azadirachta indica. Ethanol and aqueous extract of leaves and barks of A. indica (Neem) were tested against Escherichia coli and Staphylococcus aureus which are known to be resistant to various antibiotics. Neem materials which were used during this study were collected from Bugesera district precisely at Nyamata in Murama sector whereas the bacterial strains were isolated from microbiology laboratory of CHUK (Centre Hospitalier Universitaire de Kigali) and transported under safe conditions to be kept in KIST laboratory under favorable conditions for each of them. The efficiency of the extracts was studied and determined by applying different extract concentrations onto the two cultured bacterial strains using the disc diffusion method. In this study, we examined the in vitro effect of extracts of different neem (Azadirachta indica) plant (leaf and bark) on Staphylococcus aureus and Escherichia Coli. Ethanol and aqueous extracts were prepared from both dry and fresh neem’s leaves and barks. The susceptibility of tested bacteria to both extracts was determined by measuring the diameter of inhibition zones formed around plates. With the statistical test analysis, the comparison done showed that, Fresh Neem materials was found to be the most showing much effect on both Escherichia coli and Staphylococcus aureus. Comparing Neem leaves and Neem barks, always their fresh extracts were found more efficient than dry extracts; the same as ethanol extracts were more effective than aqueous extracts in all cases, S.aureus was the only bacterium susceptibly affected by these neem extracts used; while E.coli didn’t respond to any of them. The results showed that the effectiveness of the extracts was dependent of the concentration used thus the increase of extract concentration increased the inhibition zone.