The antibacterial activity of some essential oils against clinical isolates of Acinetobacter baumannii

Acinetobacter baumannii is categorized as a red alert pathogen that is increasingly associated with a high mortality rate in infected patients due to its resistance to extensive antibiotics. In this study, we evaluated the antibacterial activities of some essential oils (Oliveria decumbens, Pelargonium graveolens, Eugenia caryophyllata, Ziziphora tenuir and Trachyspermum copticum oils) against 32 clinical isolates of A. baumannii. The antibacterial evaluations and chemical composition of essential oils was determined. Thymol, eugenol, -terpineol, -citronellol and thymol were the chief portions of T. copticum, E. caryophyllata, Z. tenuir, O. decumbens and P. graveolens oils, respectively. The MIC values of oils against these clinical isolates revealed the three subsets of oils including 1T. copticum, E. caryophyllata and O. decumbens, 2Z. tenuir and 3P. graveolens oils. These oils showed the synergistic activity with amikacin, the lower Fractional Inhibitory Concentration Index (FICI) was for P. graveolens oil (0.23) and the higher FICI was for E. caryophyllata (0.325).