Abobakr M. Mahmoud¹, Rehab Mahmoud Abd El-Baky^2,, Abo Bakr F Ahmed^{2, 3}, Gamal Fadl Mahmoud Gad²

The clinical effectiveness of most of the marketed antimicrobials is found to be threatened by the rapid emergence of multidrug resistant pathogens which increase the need to find alternatives. Hundred years ago, essential oils have been known for their biologic activities in the folkloric medicine in many countries. The objective of our study was to investigate the antibacterial activity of some essential oils against different microorganisms and to study the possible effects between the tested oils and some standard antimicrobials. The antibacterial activity of 11 essential oils was evaluated against Staphylococcus aureus, E. coli, Klebseilla pneumoniae and Pseudomonas aeruginosa and 50 clinical strains isolated from different infections each alone and in combination with some standard antimicrobials using well diffusion method. Minimum inhibitory concentrations were determined using linear regression analysis. Results showed that all tested essential oils have good antimicrobial activity. As Coriander oil showed the highest antimicrobial activity against Staphylococcus aureus and E.coli followed by Origanum and Ivy oil. Cumin oil showed the highest activity against E. coli followed by Origanum oil while Chammomile and Onion oil showed the highest activity against Pseudomonas aeruginosa. In-vitro interaction between the tested antimicrobials and oils showed variable results against the tested bacteria. The results are of significance in health care system and microbial diseases treatment. As our study showed that essential oils possessed good antimicrobial activity against the tested strains. Most of essential oils/antimicrobials combinations showed synergistic effects. Essential oils can be used as adjuvant to antibiotic therapy.

chammomile, ivy, cumin, onion, essential oils, antibacterial, SEM