Investigation of the Chemical Composition and Different Effects of a Rumex dentatus Methanol Extract Against Drug Resistant Pseudomonas aeruginosa Isolates

Abstract

Background: The emergence of Pseudomonas aeruginosa as a multiple drug resistant bacteria has renewed efforts to identify alternative antibacterial materials, such as medicinal plants. Objectives: The aims of this study were to investigate the antibacterial effects of a Rumex dentatus methanol extract against drug resistant P. aeruginosa isolates and to analyze the chemical composition of this extract. Materials and Methods: Sixty strains of P. aeruginosa were isolated from urine and wound samples and identified using conventional tests, as well as 16S rDNA gene sequencing. Results: The isolates were completely resistant to the tested antibiotics, with minimum inhibitory concentration (MIC) values for ceftazidime, imipenem, and gentamicin between 256 to > 256 μg/mL, 8 to > 256 μg/mL, and 64 to > 256 μg/mL, respectively. The R. dentatus extract had a broad spectrum activity against all tested isolates and maximum growth inhibition against isolates from burn wound and urinary tract infections occurred at 200 mg/mL (22.43mm and 22.86mm, respectively). The means of the MIC and minimum bactericidal concentration (MBC) values were 25 and 50 mg/mL, respectively. The effects of a combination of the methanol extract and ceftazidime, imipenem, and gentamicin antibiotics were antagonistic. The GC-MS analysis of the methanol extract revealed a high probable presence percentage of alpha-pinene, sabinene, and eucalyptol (1, 8-cineole) that have confirmed antimicrobial activity. Conclusions: The R. dentatus methanol extract with broad spectrum activity can be viewed as an alternative to antibiotics for treatment of P. aeruginosa infection.