Abstract
BACKGROUND: Pseudomonas aeruginosa is the leading bacterial cause of otitis externa and demonstrates increasing resistance to commonly used topical antibiotics. The growing burden of antimicrobial resistance has prompted exploration of plant-derived antibacterial agents. Euphorbia neriifolia has been traditionally used for ear-related conditions; however, its activity against Pseudomonas aeruginosa from otitis externa remains insufficiently investigated. OBJECTIVE: To evaluate the in vitro antibacterial activity of fresh E. neriifolia leaf juice against P. aeruginosa ATCC 27853 and clinical isolates from otitis externa. METHODS: An in vitro experimental study was conducted using broth microdilution and disk diffusion assays. Fresh leaf juice was prepared and tested at concentrations ranging from 10% to 100%. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. Disk diffusion was performed at selected concentrations. Phytochemical constituents were analyzed using LC-MS. RESULTS: LC-MS identified multiple bioactive compounds, including quercetin, chlorogenic acid, kaempferol, gallic acid, and 7-hydroxycoumarin. MIC and MBC values for ATCC 27853 and clinical isolate 1 were 50% and 60%, respectively, while clinical isolate 2 demonstrated MIC at 60% and MBC at 70%. Disk diffusion showed dose-dependent inhibition, with inhibition zones exceeding 20 mm at 60% for ATCC 27853 and isolate 1, and at 70% for isolate 2. Ofloxacin produced larger inhibition zones than the extract across all strains. CONCLUSION: E. neriifolia leaf juice exhibits significant in vitro antibacterial activity against P. aeruginosa, including clinical isolates from otitis externa. Although less potent than ofloxacin, its bioactive profile supports further investigation as a potential adjunctive topical therapy.