Antibacterial potency of extracted essential oils of some plant species against common gram-positive and gram-negative bacteria

Abstract

Background: In the last decades, due to the rapid emergence of multidrug resistant pathogens, the antibiotic-resistance phenomenon has become a global health crisis. Therefore, there is a need to find new remedies against pathogenic microbes. Objectives: The main intention of this research was to appraise the antibacterial potency of extracted essential oils (EEOs) from various plant species versus human disease-causing bacterial strains. Materials and Methods: Antibacterial and bactericidal activity of EEOs was tested on human disease-causing strains which included Gram-positive as well as Gram-negative bacteria. Antibacterial analysis for various extracts of the different plants was performed by utilizing the method of disc diffusion and deduction of minimum inhibitory concentration (MIC) by microbroth dilution assays of the EEOs against the bacterial strains. Standard antibiotics (amoxicillin, metronidazole, rifampicin, clarithromycin, oxacillin, and clindamycin) were used to compare with EEO antibacterial activity. Results: Eclipta alba EEO was most effective against Streptococcus Pyogenes (2.06 ± 0.15), Neisseria gonorrhoeae (1.50 ± 0.20), Streptococcus aureus (0.05 ± 0.02), and Pseudomonas aeruginosa (4.56 ± 0.25). Leucas linifolia EEO was most effective against E. coli (3.13 ± 0.25) and Klebsiella Pneumoniae (4.33 ± 0.23). Bactericidal activity EEO from E. alba with minimum bactericidal concentration (MBC) ranged from 0.11 ± 0.03 to 10.60 ± 0.55; Atriplex hortensis (8.73 ± 2.62–12.07 ± 0.65); Hedyotis scandens (9.13 ± 0.50–15.30 ± 0.43); L. linifolia (0.94 ± 0.05–10.73 ± 0.20); Murraya koenigii (9.0 ± 0.55–12.90 ± 0.18); and Phlogacanthus thyrsiflorus (5.96 ± 1.15–13.0 ± 0.52). Bactericidal activity E. alba EEO was highest against S. Pyogenes (4.06 ± 0.15), N. gonorrhoeae (3.06 ± 0.40), and S. aureus (0.11 ± 0.03). L. linifolia EEO was most effective against P. aeruginosa (0.94 ± 0.05) and K. Pneumoniae (8.73 ± 0.41). Against E. coli (5.96 ± 1.15), the bactericidal activity of P. thyrsiflorus EEO was most effective. Conclusions: Comparison to the antibacterial activity of EEOs from six different plant species used in the study was more effective than the tested antibiotics. MIC and MBC values show that E. alba EEO plant species was the most effective against the tested human pathogenic bacterial strains.