Reversal of resistance in bacteria underlies synergistic effect of essential oils with conventional antibiotics

• Published in: Microbial pathogenesis 2017-05, Vol.106, p.50-59
• Main Authors: Lahmar, Aida, Bedoui, Ahmed, Mokdad-Bzeouich, Imen, Dhaouifi, Zaineb, Kalboussi, Zahar, Cheraif, Imed, Ghedira, Kamel, Chekir-Ghedira, Leila
• Format: Article
• Language: English
• Subjects: Acinetobacter baumannii - drug effects; Amoxicillin - pharmacology; Animals; Anti-Infective Agents - pharmacology; Antibiotics; Bacteria - drug effects; Bacteria - pathogenicity; beta-Lactamases - drug effects; Cell Line - drug effects; Cell Proliferation - drug effects; Cell Survival; Cyclohexenes - chemistry; Drug Combinations; Drug Resistance, Multiple, Bacterial - drug effects; Drug Synergism; Escherichia coli - drug effects; Essential oil; Gas Chromatography-Mass Spectrometry - methods; Humans; Keratinocytes - drug effects; Methicillin-Resistant Staphylococcus aureus - drug effects; Mice; Microbial Sensitivity Tests - methods; Monoterpenes - chemistry; Multi-drug-resistant bacteria; Novobiocin - pharmacology; Ofloxacin - pharmacology; Oils, Volatile - chemistry; Oils, Volatile - pharmacology; Oxacillin - pharmacology; Piperacillin - pharmacology; Plant Extracts - chemistry; Plant Extracts - pharmacology; Plant Oils - chemistry; Plant Oils - pharmacology; Sesquiterpenes, Eudesmane - chemistry; Spleen - drug effects; Synergism; Terpenes - chemistry; Tetracycline - pharmacology; Time Factors
• ISSN: 0882-4010; 1096-1208
• DOI: 10.1016/j.micpath.2016.10.018

The pervasive of bacterial resistance earnestly threaten the prevention and the treatment of infectious diseases. Therefore, scientific communities take precedence over development of new antimicrobial agents. The aim of the study was to determine antimicrobial potency of three North-African essential oils Pituranthos chloranthus, Teucruim ramosissimum and Pistacia lentiscus individually, and in combination with antibiotics, to inhibit the growth of highly resistant clinical pathogen. Bacteria clinically isolated from patients, subsequently, challenged to a panel of drugs to determine the antibiotic-resistance profiles. Drugs displaying clinically irrelevant CMI were subjected to further studies in order to rescue antibiotic actions. Singular activity of essential oils and activity when combined with an antibiotic was hence elucidated. The results obtained highlighted the occurrence of strong antibacterial potential of essential oils when administrated alone. In the interactive experiment essential oils were found highly effective in reducing the resistance of Methicillin-resistant Staphylococcus aureus to amoxicillin, tetracycline, piperacillin, ofloxacin and oxacillin and resistance of Acinetobacter baumannii to amoxicillin and to ofloxacin in interactive manner. Furthermore, the results proved synergism among essential oils and both antibiotics ofloxacin and novobiocin against the Extended-Spectrum Beta-Lactamase producing E. coli (ESBL). Time kill kinetics was performed with a combination of sub-inhibitory concentrations to confirm the efficiency and killing rate of the combination over time. Further, the hypothetical toxicity of essential oils against human keratinocytes HaCat and murine spleenocytes were examined. The chemical composition of essential oils was assessed by GC/MS analysis and the major constituents found were sabinene, limonene, terpinen-4-ol, and β-eudesmol. •Clinical wound isolates were challenged with conventional antibiotics.•Chemical composition of essential oils was determined by GC/MS.•Synergistic activity was detected for most of the AB-EO combinations.•Time kill kinetics confirmed the synergism.•The cytotoxicity assay upon HaCat and spleen cells was assessed.