Antibacterial Properties of Commercially Available Cayeput Essential Oil Against Different Gram-Positive and Gram-Negative Bacteria

Abstract

Essential oil and leaf extracts of Melaleuca leucadendra L. demonstrated a series of biological activities of interest, including antioxidant, antimicrobial, antitumoral and anti-inflammatory properties. The aim of the current study was an in vitro evaluation of the antimicrobial activity of the cajeput essential oil against 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™), Staphylococcus aureus subsp. aureus Rosenbach (ATCC® 25923™), 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™) to assess the possible use of this oil in preventing infections caused by these pathogens. The cajeput essential oil was provided by Polish essential oil manufacturers (Bamer®, Włocławek, Poland). Antimicrobial susceptibility of the tested strains was performed by the Kirby-Bauer disc diffusion method. Our research has shown that cajeput essential oil exhibits antibacterial properties. Gram-positive bacteria were the most susceptible to commercial cajeput oil, which may indicate that the active biological substances in cajeput essential oil (including phenolic acids, tannins, etc.) may be potential agents against bacterial infections. Among Gram-negative bacteria, only Pseudomonas aeruginosa (Schroeter) Migula (ATCC® 27853™) strain was resistant to the cajeput essential oil. We did not observe statistically significant changes in the zone of growth inhibition after the application of cajeput essential oil compared to the control samples (96% ethanol). Our study may suggest that the use of cajeput essential oil may be helpful for a wide range of bacterial infections in veterinary, aquaculture, medicine, and beyond.