J Appl Biol Biotech. Volume: 8, Issue: 1, Jan-Feb, 2020 - 84-89 DOI: 10.7324/JABB.2020.80114 Short Communication Cymbopogon giganteus Chiov. essential oil: Direct effects or activity in combination with antibiotics against multi-drug resistant bacteria Habib Toukourou 1 2, Hope Sounouvou 2, Lucy Catteau 1, Fatiou Toukourou 2, Françoise Van Bambeke 2, Fernand Gbaguidi 3, Joëlle Quetin-Leclercq 4 Author Affiliations 1 Laboratoire de Chimie Pharmaceutique Organique, Ecole de Pharmacie, Faculté des Sciences de la Santé, Université dAbomey-Calavi, Campus du champ de Foire, Cotonou 01BP 188, Benin. 2 Pharmacognosy Research Group, Louvain Drug Research Institute, Université catholique de Louvain, 1200 Bruxelles, Belgium. 3 Laboratoire de Microbiologie et des Technologies Alimentaires, Champ de Foire ISBA, Faculté des Sciences et Techniques, Université dAbomey-Calavi, Cotonou BP 526, Benin. 4 Pharmacologie cellulaire et mol\éculaire, Louvain Drug Research Institute, Université catholique de Louvain, 1200 Brussels, Belgium. Abstract The discovery of new antimicrobial agents is necessary due to the emergence of multi-drug bacterial resistance. The aim of this work was to study the direct and indirect antimicrobial activity of a Beninese sample of Cymbopogon giganteus essential oil (EOCG) on multi-drug resistant clinical bacteria, its chemical composition, and its cytotoxicity. Direct antimicrobial activity was tested by determination of minimal inhibitory concentration (MIC), and indirect activity, by determining Fractional Inhibitory Concentration Index using checkerboard [fractional inhibitory concentration indices (FICI); synergy: FICI ≤ 0.5; additivity: 0.5 < FICI ≤ 1]. EOCG composition was determined by GC -MS and GC-FID and cytotoxicity was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphényltetrazolium bromide (MTT) assay. p-Menthane derivatives (54.87%) and limonene (12.07%) were detected as major compounds by GC analysis. Our results confirmed the direct antimicrobial activity of EOCG, but here on clinical resistant strains (MIC from 0.125% v/v to 0.5% v/v). We also show synergistic effects between EOCG and amoxicillin with FICI ranges of 0.12– 0.5 against two Escherichia coli resistant clinical strains, synergistic to additive effects between EOCG and colistin or oxacillin/ampicillin, respectively, against Pseudomonas aeruginosa PA544 and Staphylococcus epidermidis SECN361 (two resistant clinical isolates). Our results also indicate that EOCG had low cytotoxicity (IC50: 67.06 ± 2.694 μg/ml). Keywords: Cymbopogon giganteus, multi-drug resistant bacteria, essential oil-antibiotic interaction, synergy. Citation: Toukourou H, Sounouvou H, Catteau L, Toukourou F, Van Bambeke F, Gbaguidi F, et al. Cymbopogon giganteus Chiov. essential oil: Direct effects or activity in combination with antibiotics against multi-drug resistant bacteria. J Appl Biol Biotech. 2020;8(1):84-89. Copyright: Author(s). This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited.