Antagonistic interaction between Rosa damascena Mill. extract and gentamicin against Klebsiella pneumoniae and its phytochemical study, in vitro

Background and Objective: Antibiotic resistance of bacteria is threatening medical achievements in healing infections. In the United States, for example, 2 million people are affected by these organisms annually and among them 23000 individuals pass away. Medical plants are rich sources for developing antibacterial agents especially if we find synergestic interaction between them and antibiotics. The petals of Rosa damascena Mill. (PR) is one of those sources with many therapeutic properties, as result, the aim of this study is to evaluate antibacterial effect and interaction of its extract with gentamicin on a multidrug-resistant (MDR) bacteria.Materials and Methods: In this experimental study, total phenolic content (TPC), total flavonoids content (TFC), Anthocyanin content and Antioxidant activity of hydroalcoholic extract of PR were determined by Folin-Ciocalteu, Aluminum chloride colorimetric, pH-differential and DPPH free radical method. Minimal inhibitory concentration (MIC) of PR extract and gentamicin on the standard strain of Klebsiella pneumoniae (ATCC 700603) were determined by resazurin-microdilution assay, each test was repeated for three times, and finally for determining the interaction between extract and gentamicin we used checkerboard method. Data were analyzed using SPSS software (version18), Kruskal-Wallis and Mann-Whitney tests.Findings: TPC, TFC, anthocyanin content and antioxidant activity of this extract were measured 57.70 mg equivalent Gallic acid/g dried extract, 10.1 mg equivalent Rutin/g dried extract, 535.36 mg/g and 39 μg/ml (IC50) respectively. MIC of PR on K. pneumoniae (4096 μg/ml) was reported by detecting the last wells with the lowest concentration of agents that had no color change from blue to pink and finally Minimum bactericidal concentration (MBC) of PR on K. pneumoniae (8192 μg/ml) were determined by adding 10 μl of the wells that had no color change on agar plates, the lowest concentration that caused 99.9% reduction in the original inoculum was considered as MBC. Fractional inhibitory concentration (FIC) index for these two agents was more than 2 that showed antagonistic interaction between them. Conclusion: Results indicated that PR is a good source for phenolic components and these components could be purified and used against MDR bacteria. Our in vitro study showed antagonistic interaction between PR extract and gentamicin that could be an important point for physicians to pay more attention on drug history of their patients while administering gentamicin for infections induced by K. pneumoniae, although more studies in in vivo conditions are needed.

Keywords:

Rosa damascena Mill , Klebsiella pneumoniae , Flavonoids , drug interaction