Chemical composition, antibacterial and antioxidant activities of some essential oils against multidrug resistant bacteria

Introduction: Antibiotic resistance is a serious threat to both human and environmental ecosystems. Alternatives to conventional antimicrobial therapy such as essential oils (EOs) are needed. The aim of the present study was to investigate the chemical composition, antibacterial and antioxidant activities of some commercial EOs. Methods: In this study, six selected EOs were screened against four bacterial strains identified as resistant to antibiotics: Staphylococcus aureus, Escherichia coli, Enterococus faecalis and Klebsiella pneumonia, as well as two sensitive bacterial strains: Staphylococcus aureus and Escherichia coli. Isolated bacterial strains were characterized and identified by morphological and biochemical tests. Commercially EOs of Rosmarinus officinalis L., Zingiber officinale Roscoe., Melaleuca alternifolia Cheel., Cymbopogon winterianus, Salvia sclarea L. and Syzygium aromaticum were evaluated for their antibacterial and antioxidant activities. A GC/MS was carried out to analyze the composition of the EOs investigated. Results: From this study, the results obtained reveal that no bacterial strain tested was resistant to any of the studied EOs. The EOs obtained from rosemary contained high amount of β-Pinene, ginger oil was rich in Zingiberene and the tea tree oil was dominated by α-Carene. Linalool was the major component in lemon and clary sage. Clove oil contained high amount of 3-Allylguaiacol. The antioxidant results showed a noticeable antioxidant activity in β-carotene-linoleic acid system in all EOs. While, in DPPH method, only clove showed activity. Conclusion: These antibacterial and antioxidant activities support further studies to discover new chemical structures that can inhibit the growth of multiresistant bacteria.