Investigation of the Antibacterial Activity of Essential Oil from Cymbopogon citratus Leaves against Gram-Negative Bacteria ^†

Gram-negative bacteria cause a multitude of infections in humans and, over time, many have developed resistance to conventional antibiotics, making available treatments less effective. Given this scenario, several studies have explored natural plants as a possible therapeutic approach, highlighting the essential oil of Cymbopogon citratus, commonly known as Lemongrass. Therefore, the scope of this work is to investigate reports in the literature about the antibacterial activity of lemongrass essential oil against Gram-negative bacteria. A narrative review was carried out using the PICo strategy with the following guiding question: how effective is Cymbopogon citratus essential oil (P) as a therapeutic modality (I) considering its antibacterial properties (Co)? The search for articles was carried out in the PubMed, Virtual Health Library (BVS), Scielo, and CAPES databases, using the descriptors “Cymbopogon Citratus”, “essential oil”, “lemon grass”, “antibacterial activity”, and “Gram-negative bacteria” combined with Boolean operators (OR and AND). Original studies that addressed the antibacterial activity of the vegetable’s essential oil in Portuguese, English, or Spanish were included and duplicate works were excluded. After screening, the final sample consisted of 14 articles. The studies were primarily in vitro trials. In a test with Pseudomonas aeruginosas, the inhibitory activity of the compound was from a concentration of 5%, while for Salmonella enteritidis, it was from 2.5%. Concomitantly, the vegetable’s essential oil showed a significant inhibitory effect with halos ranging between 12 and 23 mm and minimum inhibitory concentration (MIC) of 3.90 µg/mL, against strains of the Aeromonas caviae complex. Against strains of Proteus penneri, Escherichia coli, and Klebsiella oxytoca, different degrees of inhibition were observed, all exhibiting halos greater than or equal to 11 mm. These results point to the essential oil of C. citratus as a promising alternative to control and combat bacterial infections, highlighting its bactericidal action at relatively low concentrations