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

The emergence of Pseudomonas aeruginosa as a multiple drug resistant bacteria has renewed efforts to identify alternative antibacterial materials, such as medicinal plants. 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. Sixty strains of P. aeruginosa were isolated from urine and wound samples and identified using conventional tests, as well as 16S rDNA gene sequencing. 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. The R. dentatus methanol extract with broad spectrum activity can be viewed as an alternative to antibiotics for treatment of P. aeruginosa infection.