Bactericidal property of myrrh oil and two formulations against standard bacterial strains and multidrug-resistant clinical isolates with GC/MS chemical profiling

Myrrh is the resinous exudate obtained by the incision of Commiphora molmol trees (Family Burseraceae). The bactericidal activity of its total oil (extracted by hexane) was compared to its essential oil (MEO, 5% v/v) using viable count technique against Staphylococcus aureus (S. aureus ATCC 6538) and Pseudomonas aeruginosa (Ps. aeruginosa ATCC 9027). MEO exhibited a better activity with >99.999% killing of both tested strains after 2h contact time. MEO (5% v/v) was tested using the same technique against four multidrug resistant isolates; S. aureus (MRSA, sputum), Escherichia coli (E. coli, urine), Ps. aeruginosa (wound) and Klebsiella pneumonia (K. pneumonia, sputum). Highest bactericidal activity was observed against Ps. aeruginosa and least activity was against K. pneumonia (99.59 and 54.04% killing, respectively after 2h contact time). A cream and mouthwash were formulated using 5% v/v MEO. The cream showed a better activity against Ps. aeruginosa than S. aureus (86.68 and 51.11 % killing, respectively after 2h contact time). A 75% reduction in oral aerobic bacteria was observed after gargling the mouthwash for 2 min. This reduction was sustained for 20-30 min. followed by slow gradual increase in the number of recovered bacteria. GC/MS analysis allowed the identification of 17 and 9 compounds representing 92.01 and 97.99% of the total and essential oil, respectively. Furano-eudesma-1,3-diene (15.99%) and 2-acetoxy-furano-diene (26.82%) were the major identified compounds in the total and essential oil, respectively. These results indicate that Myrrh essential oil is a promising antibacterial agent that can be formulated against multidrug resistant bacterial strains.