Synergistic Effects of Essential Oils and Antibiotics Against Some Bacterial Strains

The emergence of antibiotics resistances become an alarming situation due to the resurgence of cases. Scientific community explore therapeutics alternatives, including essentials oils and their combination with antibiotics. The designed study aimed to evaluate the combined effects of essentials oils from Drypetes Gosswelleri, Echinops giganteus, Melaleuca leucadendron essentials oils and antibiotics against strains implicated in infectious deseases. The antibacterial effect of essentials oils and antibiotics (Ciprofloxacine and Ceftriaxone) was carried out against Pseudomonas aeruginosa, Klebsiella pnemoneae, Salmonella enteritidis, Staphylococcus aureus and Bacillus cereus strains using the microdilution method. The synergistic effects were studied by the isobologram method to conclude on the interaction type. The results revealed that the essential oils were active against all the tested bacteria. Drypetes Gosswelleri EO showed the strongest activity with MICs ranging from 1.46 μg/mL to 11.71  µg/mL, followed by Echinops giganteus essential oil with MICs ranging from 2.92 µg/mL to 23.43 µg/mL and Melaleuca leucadendron had the lowest activity with MICs ranging from 5.88µg/mL to 750µg/mL. The combinations realized between Drypetes Gosswelleri and Echinops giganteus EOs and with two antibiotics use to evaluate the interaction type agains Salmonella enteritidis and Staphylococcus aureus. MICs obtained with the combinations are lower than those obtained with the EOs and antibiotics tested individually. The isobolograms plotted inform about a synergistic effects of combinations made with Drypetes Gosswelleri, Echinops giganteus EOs, Ciprofloxacin and Ceftriaxone against S. enteritidis and S. aureus strains. Based on the results obtained, the combinations between EOs and the antibiotocs, represent an interesting therapeutic alternative. Keywords: antibacterial, essential oil, combination, isobolograms, synergistics, Minimale Inhibitory Concentration, Minimale Bactericidal Concentration