Sensibility profile of multi-drug resistant Shigella strains to essential oils from Drypetes gosseweleri S.Moore, Ocimum gratissimum L. and Cymbopogon citratus DC Stapf

Background: The high prevalence of multidrug-resistant Shigellosis is a public health issue in many developing countries. In rural areas of African’s countries, especially in Cameroon, the use of medicinal plants as treatment is an important alternative solution to treat Shigellosis. The present study aims to evaluate the antibacterial activity of the essential oils from Drypetes gossweileri Stem Bark, Ocimum gratissimum leaves, Cymbopogon citratus leaves and their combinations against multidrug-resistant strains of Shigella. Material and Methods: 05 clinical strains of Shigella isolated from patients with diarrhoea including Shigella flexneri and 4 other strains of Shigella spp (strain a, strain b strain c and strain d) were selected and their antibiotic profile established using agar test diffusion with Ciprofloxacin, Nalidixic acid, Tetracycline, Amoxicillin, Cefotaxime, Erythromycin and Cotrimoxazole as reference drugs. The essential oils were extracted from each plant using hydrodistillation process. The activity of Ciprofloxacin®, essential oils and their combination formulated in the following ratios (w/w/w): C1: 1/1/1; C2: 2/1/1; C3: 1/2/1, C4:1/1/2 was evaluated microdilution assay. Results: Antibiotic susceptibility tests revealed that most Shigella isolates (n = 4) were resistant to six antibiotics tested. Ciprofloxacin (40 %) Nalidixic acid (60 %), Tetracycline (80 %), Amoxicillin (100 %), Cefotaxime (80 %) Erythromycin (100 %) and Cotrimoxazole (80%) were the profiles found in the 4 isolates of Shigella spp and S. flexneri. All essential oils have demonstrated good antibacterial activities with Minimal Inhibitory Concentration (MIC) ranging from 0.07812 mg/mL to 6,25 mg/mL. However, Drypetes gossweileri essential oil had shown a higher Shigellicide property with a MIC ranging from 0.07812 mg/mL against Shigella flexneri to 0.3125 mg/mL against strain a. All combinations were most active, but the C2 combination (2/1/1) is the one that showed a higher antibacterial property with CMI ranging from 0.012207 to 1.5625 mg/mL. Conclusion: The susceptibility of Shigella to essentials oils and their combination justified the use of these plants in traditional medicine to treat Shigellosis.
Keywords: Antibacterial activity, Combinations, Essential oils, Medicinal plants, Multidrug-resistant, Shigellosis.