Antimicrobial activity of Azadirachta indica (Neem) leaves against E. colii isolates from bovine subclinical mastitis

Abstract

Background/ Aim: The leading cause of financial losses in the dairy industry has been subclinical mastitis, and the problem of antibiotic resistance has made plant-based treatment seem like the most sensible option. To evaluate the phytochemical composition and in vitro antibacterial activity of methanolic extract of Azadirachta indica (Neem) leaf against Escherichia coli isolated from mild mastitis in cows. Methodology: The in vitro antibacterial effectiveness of Azadirachta indica (Neem) methanolic leaf extract against E. colii isolated from the milk of cows with moderate mastitis was evaluated. The uidA gene, approximately 556 bp long, served as the target for PCR and for phenotypic verification of the isolates. Agar disc diffusion was used to test the extract (31.25-500 µg/mL), and ANOVA (p < 0.05) was used to quantify the inhibitory zones after 24 hours. Results: Phytochemical screening indicates that the plant contains flavonoids, tannins, alkaloids, saponins, glycosides, and phenolic compounds. The extract showed dose-dependent antibacterial activity, with the largest inhibition zones observed for E. colii (10.5-14.5 mm). According to the one-way ANOVA, the 250 mg/ml concentration was as active as streptomycin, and the analysis also revealed significant variation in effects across concentrations (p < 0.05). Conclusion: The methanolic extract Azadirachta indica (Neem) leaves shows very effective antibacterial activity against the most common bacteria that cause mastitis. It could be a potential natural alternative or a partner drug in the treatment of bovine subclinical mastitis.