In vitro antibacterial activity of peppermint

Antibacterial activities of different forms of peppermint (Mentha piperita) viz., aqueous infusion, decoction, juice and essential oil were investigated against 100 isolates belonging to I I different species of Gram -ve bacilli viz., Escherichia coli (30), Klebsiella pneumoniae (25), Pseudomonas aeruginosa (15), Salmonella typhi (5), S. paratyphi A (1), S. paratyphi B (1), Proteus mirabilis (10), P. vulgaris (2), Shigella dysentriae (5), Yersinia enterocolitica (1), and Enterobacter aerogenes (5). The screening was performed by standard disc diffusion method. Essential oil of peppermint exhibited highest antibacterial activity with 11.78 mm mean zone of inhibition. The juice of peppermint also possessed antibacterial activity with 10.41 rum mean zone of inhibition, while all isolates were totally resistant to aqueous infusion and decoction of peppermint.