Inhibition by the essential oils of peppermint and spearmint of the growth of pathogenic bacteria

The effects of the essential oils of peppermint (Mentha piperita L.), spearmint (Mentha spicata L.) and Japanese mint (Mentha arvensis L.), of four major constituents of the essential oil of peppermint, and of three major constituents of the essential oil of spearmint, on the proliferation of Helicobacter pylori, Salmonella enteritidis, Escherichia coli O157:H7. methicillin-resistant Staphylococcus aureus (MRSA) and methicillin sensitive Staphylococcus aureus (MSSA) were examined. The essential oils and the various constituents inhibited the proliferation of each strain in liquid culture in a dose-dependent manner. In addition, they exhibited bactericidal activity in phosphate-buffered saline. The antibacterial activities varied among the bacterial species tested but were almost the same against antibiotic-resistant and antibiotic-sensitive strains of Helicobacter pylori and S. aureus. Thus, the essential oils and their constituents may be useful as potential antibacterial agents for inhibition of the growth of pathogens.