Antibacterial activity of essential oil extracted from Citrus hystrix (Kaffir Lime) peels: An in vitro study

The exploration of antimicrobial activities from various herbal plants such as Citrus species might be a solution to reduce the emergency of antimicrobial resistance. This study was conducted to determine the chemical composition of Citrus hystrix essential oil (CHEO) and its antibacterial activity against a broad range of Gram positive and Gram negative bacteria. CHEO was extracted from the peels of kaffir lime by steam distillation. The chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS). In vitro antibacterial activity was determined by the agar disk diffusion and broth macrodilution methods against 6 standard bacterial strains as well as 39 clinical bacterial isolates. GC-MS revealed twenty-seven compounds in CHEO with most predominant compounds like; D-limonene, followed by beta-pinene and sabinene. CHEO had inhibitory effects on all tested bacterial isolates except for Klebsiella pneunioniae, Salmonella paratyphi A, Salmonella. enteritidis, Edwardsiella tarda and Pseudomonas aeruginosa. Gram positive bacteria were generally more susceptible than Gram negative bacteria (ranged MIC; 1.0-8.0 mg/mL vs. 8.0 to >16.0 mg/mL) with Staphylococcus aureus and Elizabethkingia meningoseptica being the most susceptible. These findings demonstrated that CHEO has a potential to be developed as an antibacterial agent to combat the emerging antimicrobial resistant bacteria.