ANTIBACTERIAL PROPERTIES OF COMMERCIAL PEPPERMINT ESSENTIAL OIL AGAINST SOME GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA

The authors of this article conducted research and studied the antibacterial properties of commercial peppermint essential oil (PEO) against several gram-positive and gram-negative bacteria provided by Polish manufacturers of essential oils (Naturalne Aromaty sp. z o.o., Klaj, Poland). Therefore, to conduct research with the aim of to study the antibacterial properties of commercial peppermint essential oil (PEO), an antimicrobial susceptibility test (Kirby-Bauer diffusion test) was used to measure diameters of bacterial growth inhibition zones). In the current study, Gram-negative strains such as Escherichia coli (Migula) Castellani and Chalmers (ATCC® 25922™ ), Escherichia coli (Migula) Castellani and Chalmers (ATCC® 35218™ ), Pseudomonas aeruginosa (Schroeter) Migula (ATCC® 27853™ ) and Gram-positive strains such as Staphylococcus aureus subsp. aureus Rosenbach (ATCC® 29213™ ), methicillin-resistant (MRSA), mecA positive Staphylococcus aureus (NCTC® 12493), Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 51299™ ) (resistant to vancomycin; sensitive to teicoplanin) and Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 29212™ ) were used. Results of the current study revealed that resistant to the PEO were Gram-negative bacterial strains, such as E. coli (Migula) Castellani and Chalmers (ATCC® 35218™ ) and P. aeruginosa (Schroeter) Migula (ATCC® 27853™ ) strains. The authors found that the diameters of the inhibition zones after application of PEO were similar to the control samples (96% ethanol). It was also found that after the application of REO, the increase in the diameters of the inhibition zones was 60.3% (p < 0.05) for the Escherichia coli strain (Migula) Castellani and Chalmers (ATCC® 25922™ ) compared to control samples (96% ethanol ). Accordingly, Gram-positive strains such as S. aureus subsp. aureus Rosenbach (ATCC® 29213™ ) and methicillin-resistant S. aureus (NCTC® 12493) were equally resistant to PEO, similarly. On the other hand, Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 29212™ ) and Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 51299™ ) were sensitive to PEO. After the application of PEO, the largest diameters of inhibition zones were observed for the E. faecalis strain. The results suggest that commercial peppermint essential oil provided by Polish essential oil manufacturers (Naturalne Aromaty sp. z o.o., Kłaj, Poland) possesses some noteworthy antimicrobial properties. In vivo studies are necessary to calculate the effective dose of EOs and determine their possible side effects and toxicity.