RESUMO
Objective: To find the efficacy of peppermint oil against selected bacterial pathogens and compare with their susceptibility towards antibiotics. Methods:Peppermint oil was evaluated for activity against Bacillus cereus, Bacillus subtilis, Escherichia coli, Staphylococcus aureus (S. aureus), Klebsiella pneumoniae and Pseudomonas aeruginosa. The antibacterial assay was evaluated using agar well diffusion method and the viability of the organisms (MIC and MBC) was determined at different concentrations using broth dilution method. Results: Peppermint oil was found to be effective against all the gram positive and gram negative organisms tested. A progressive effect of antibacterial activity with increase in concentration of oil was observed. The test organisms were found to be inhibited by peppermint oil at lower concentration in broth dilution method as compared with agar diffusion method. When comparing the assessment of the inhibitory effect of peppermint oil, broth dilution was found to be more effective as compared with agar diffusion method. Except S. aureus, the remaining organisms tested in the present study were found to possess multiple drug resistance. However, peppermint oil was found to be effective against these bacterial strains studied. Conclusions:Hence, with such broad spectrum activity of peppermint oil, it can be further recommended in the treatment of the infections caused by these multi-drug resistant bacteria.