Nevertheless, synthetic compounds may have the risk of antimicrobial resistance or adverse drug reaction (ADR). Meanwhile, herbal drugs are reported to be less toxic and less harmful than synthetic ones. 3 Kaffir lime is one of the plants that has been used as herbal medicine. 2 Kaffir lime, with the scientific name Citrus hystrix DC, is a member of the genus Citrus, a part of the family Rutaceae. It is widely grown in An Giang province in the Mekong Delta region of Vietnam, where the soil is suitable for many types of medicinal herbs. 4 According to previous studies, Citrus hystrix has antioxidant, antibacterial, and antimicrobial, 5-8 anticancer, 9-10 and anti-inflammatory effects. 11 Furthermore, this plant is also used as a natural insecticide (botanical insecticide), [12][13] an essential ingredient in aromatherapy, [14][15] and also as an antidandruff. 16 The antimicrobial activities observed in Citrus hystrix DC can be attributed to the presence of essential oils found in various parts of the plant, including the leaves, fruits, and seeds. However, it is worth noting that the majority of essential oil production is typically derived from the fruit of Citrus hystrix. Previous research findings have indicated that essential oils extracted from both the leaves and peel of Citrus hystrix possess antimicrobial properties. Most production of essential oil was from the fruit. Previous results showed that essential oils from the leaf and peel of Citrus hystrix possessed antimicrobial activities against Salmonella typhi, Escherichia coli, Streptococcus mutans, Staphylococcus aureus, Saccharomyces cerevisiae, and Candida albicans. [17][18][19] Similarly, research involving ethanolic extracts and the combination of extracts from the peels of various citrus fruits revealed that two or three extracts of peel powder exhibited significant antibacterial activity against common pathogens such as Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. 20 A prior work used GC-MS to determine the chemical composition of Kaffir lime fruit peel oil, a volatile oil derived from the fruit peel of Citrus hystrix DC. L-limonene, -terpineol, 2--pinene, terpinene-4-ol,terpinene, and -terpinolene were the main components. 4 Salmonella typhimurium ATCC 13311, Escherichia coli ATCC 25922, Bacillus