title: Synergistic effect of Myrtus communis L. essential oils and conventional antibiotics against multi-drug resistant Acinetobacter baumannii wound isolates.
abstract: Acinetobacter baumannii is a rapidly emerging, highly resistant clinical pathogen with increasing prevalence. In recent years, the limited number of antimicrobial agents available for treatment of infections with multi-drug resistant (MDR) strains reinforced tendency for discovery of novel antimicrobial agents or treatment strategies. The aim of the study was to determine antimicrobial effectiveness of three Myrtus communis L. essential oils, both alone and in combination with conventional antibiotics, against MDR A. baumannii wound isolates. The results obtained highlighted the occurrence of good antibacterial effect of myrtle oils when administered alone. Using checkerboard method, the combinations of subinhibitory concentrations of myrtle essential oils and conventional antibiotics, i.e. polymixin B and ciprofloxacine were examined. The results proved synergism among M. communis L. essential oils and both antibiotics against MDR A. baumannii wound isolates, with a FIC index under or equal 0.50. Combination of subinhibitory concentrations of essential oils and ciprofloxacin most frequently reduced bacterial growth in synergistic manner. The similar has been shown for combination with polymyxin B; furthermore, the myrtle essential oil resulted in re-sensitization of the MDR wound isolates, i.e. MICs used in combination were below the cut off for the sensitivity to the antibiotic. Time-kill curve method confirmed efficacy of myrtle essential oil and polymyxin B combination, with complete reduction of bacterial count after 6h. The detected synergy offers an opportunity for future development of treatment strategies for potentially lethal wound infections caused by MDR A. baumannii.
authors.affiliation: Department of Biology and Ecology, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovica 2, 21 000 Novi Sad, Vojvodina, Serbia.
authors.forename: Verica
authors.initials: V
authors.lastname: Aleksic
authors.affiliation: Department of Chemistry, Biochemistry and environmental protection, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovica 3, 21 000 Novi Sad, Vojvodina, Serbia.
authors.forename: Neda
authors.initials: N
authors.lastname: Mimica-Dukic
authors.affiliation: Department of Chemistry, Biochemistry and environmental protection, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovica 3, 21 000 Novi Sad, Vojvodina, Serbia.
authors.forename: Natasa
authors.initials: N
authors.lastname: Simin
authors.affiliation: Health Center "Aleksinac", Hygienic and Epidemiological Service, Momcila Popovica 114, 18220 Aleksinac, Serbia.
authors.forename: Natasa Stankovic
authors.initials: NS
authors.lastname: Nedeljkovic
authors.affiliation: Department of Biology and Ecology, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovica 2, 21 000 Novi Sad, Vojvodina, Serbia. Electronic address: petar.knezevic@dbe.uns.ac.rs.
authors.forename: Petar
authors.initials: P
authors.lastname: Knezevic
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D004357:Drug Synergism; D008401:Gas Chromatography-Mass Spectrometry; D008826:Microbial Sensitivity Tests; D031651:Myrtus / Q000737:chemistry*; D009822:Oils, Volatile / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry / Q000494:pharmacology*; D011112:Polymyxin B / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D009822:Oils, Volatile; D010938:Plant Oils; D002939:Ciprofloxacin; D011112:Polymyxin B
keywords: Acinetobacter baumannii; Antimicrobial agents; Essential oils/Myrtus communis; Multi-drug resistant; Synergism