Antibacterial Activity of Ethanolic Extract of Matricaria chamomilla, Malva cylvestris, and Capsella bursa-pastoris against Multidrug-Resistant Pseudomonas aeruginosa Strains

Background: This study aimed to determine antibacterial activity of ethanolic extract of Matricaria chamomilla (chamomile), Malva sylvestris, and Capsella bursa-pastoris against multi-drugresistant (MDR) clinical isolates of Pseudomonas aeruginosa. Methods: The plants were collected from Ziarat village of Gorgan, Iran in April 2019. The required parts of the plants were separated and completely dried in the shade. After grinding, extraction was performed by maceration method. The extract was dried at 37°C for 24 hours. To obtain a concentration of 50 mg/mL of each extract, 500 mg of the dried plant extract was dissolved in 10 mL 5% dimethyl sulfoxide and sterilized by filtration through a 0.45 µm membrane filter. For the antibacterial assay, agar well diffusion and broth microdilution methods were used. Results: Based on the results, ethanolic extracts of M. sylvestris and Capsella bursa-pastoris did not show any antibacterial activity against MDR P. aeruginosa isolates in both antibacterial assays. No inhibitory effect was observed for ethanolic extract of chamomile against P. aeruginosa isolates in agar well diffusion method as well. In broth microdilution method, the extract of chamomile leaves showed inhibitory effect and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined as 12.5 and 25 mg/mL, respectively. Conclusions: In this study, the extract of ethanolic chamomile leaves showed antibacterial activity against the MDR P. aeruginosa isolates. Thus, it can be used in the production of antibacterial agents, and it is a good option for protection against pathogenic microorganisms, as well as P. aeruginosa.