Antibacterial Activity of Lavandula mairei Humbert Essential Oil Against Carbapenem-resistant Acinetobacter baumannii

Abstract

Introduction: Nosocomial infections associated with a carbapenem-resistant Acinetobacter baumannii (CRAB) are considered as a significant challenge in the Intensive care units’ (ICU) critically ill patients. Lack of new antimicrobial agents to treat infections caused by this multi-drug resistant microorganism reinforces the exploration of novel strategies to encounter and control this infection. Thus, the aim of the study was to evaluate, for the first time, the antibacterial effectiveness of the Lavandula mairei Humbert essential oil (EO) against a CRAB isolated from the hospital environment of the two ICUs. Materials and Methods: Carbapenemase encoding genes were detected by the polymerase chain reactions and sequencing methods. The chemical composition of Lavandula mairei (EO) was determined by a gas chromatography-mass spectrometry analysis, and its antibacterial activity was evaluated by a disk diffusion and broth microdilution methods. Results: The OXA-23 and NDM-1 variants were revealed in the selected strains. Twenty-six compounds were identified in the Lavandula mairei EO, in which carvacrol was the most dominant one (77.32%). All the tested CRAB strains showed a wide sensitivity to the oil, with the inhibition zones’ diameters ranging from 28.67±1.15 mm to 40±2.00 mm, and a bactericidal effect proved by the similarity of minimal inhibitory and bactericidal concentrations values (0.39-3.125 µL/ml). Conclusion: These findings remain very promising for the future use of Lavandula mairei EO as a source of the natural antibacterial agents.

Keywords

• antibacterial activity
• carbapenem-resistant acinetobacter baumannii
• essential oils
• lavandula mairei humbert
• nosocomial infections