Antibacterial Effect of Neem Extracts (Leaf and Bark) Against E.Coli

Abstract

The rise of antibiotic-resistant bacteria has increased the need for effective plant based antimicrobial agents. Neem (Azadirachta indica), a widely used medicinal plant, contains numerous bioactive compounds with reported antibacterial properties. This study investigates the antibacterial effects of neem leaf and bark aqueous extracts against Escherichia coli, a common pathogen found on human skin. Skin swabs were collected from students of Federal University Gashua, and E. coli was isolated and cultured using standard microbiological procedures. Neem leaf and bark were collected, shade-dried, ground into powder, and extracted using aqueous solvent. Antibacterial activity was evaluated using the agar well diffusion method, while the minimum inhibitory concentration (MIC) was determined through serial dilution. Results showed that both neem leaf and bark extracts exhibited inhibitory effects against E. coli, with the leaf extract producing a larger zone of inhibition (3.5 cm at 10⁻¹ concentration) than the bark extract (3.1 cm at 10⁻¹). Activity decreased with further dilution, and no inhibition was observed from 10⁻⁴ onward. The findings demonstrate that neem leaf and bark possess antibacterial properties and could serve as potential natural alternatives to synthetic antibiotics. The study highlights the relevance of neem in developing affordable, plant- based treatments for bacterial infections, particularly in rural communities where access to antibiotics is limited.