Background: Some medicinal plants contain compounds that have antimicrobial activity against pathogenic bacteria. Some pathogenic bacteria, such as Pseudomonas aeruginosa, become resistant to existing antibiotics every year, making treatment of infections caused by such bacteria a challenge. Escherichia coli bacteria also cause numerous infections in the body and cause many deaths every year. Therefore, considering the importance of this issue, this study was conducted to investigate the antibacterial properties of ethanolic and chloroform extracts of the tarragon plant (Artemisia dracunculus), which has many uses in traditional medicine, against some pathogenic factors (biofilm, swarming, pyocyanin and hemolysin formation) of Escherichia coli and Pseudomonas aeruginosa, which are two important and dangerous bacteria.
Material and Methods: Ethanolic and chloroform extracts of the plant were prepared using chloroform and 85% ethanol. Broth macrodilution method was used to determine the minimum inhibitory concentration (MIC) of the extracts, then the effect of the extracts on some pathogenic factors such as biofilm formation, hemolysin, pyocyanin and swarming in the target bacteria was evaluated.
Results: The obtained MICs showed that ethanolic and chloroformic extracts of these plants can inhibit the growth of the studied bacteria. They also affect the production of some virulent factors such as hemolysin, pyocyanin, biofilm formation and swarming. In Pseudomonas aeruginosa, pyocyanin and hemolysin productions were reduced by ethanolic extract of tarragon, and biofilm production and swarming were reduced by both extracts. In Escherichia coli, hemolysin and biofilm productions were reduced by both ethanolic and chloroformic extracts, and in the swarming test, chloroformic extract was able to reduce the movement of Escherichia coli population.
Conclusion: Plant extracts can inhibit the production of some bacterial pathogenic factors and may be used in combination with antibiotics to combat resistance and side effects.