Effect of Euphorbia neriifolia L. leaf juice on the growth of Pseudomonas aeruginosa from otitis externa: an in vitro study

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.