In Vitro Antibacterial Activity of Rheum ribes Extract Obtained from Various Plant Parts Against Clinical Isolates of Gram-Negative Pathogens

Rheum ribes is among the polygonaceae famil y which is endemic in iran and a fewneighboring countries. in this investigation, antibacterial effects of root , stalk and leavesextracts of rheum ribes on a few common clinical isolates of gram negative pathogens werestudied, using the cup plate and paper dis c methods. gram negative microorganisms studiedwere escherichia coli, klebsiella pneumoniae, proteus spp., pseudomonas aeruginosa andneisseria gono rrhoeae.for examination of pathogenic microorganisms in the cup plate and disc diffusion method,methanolic extracts of different plant parts at concentrations of 250 and 500 micrograms percup or disc, were used .the root and leaves extracts hav e demonstrated significant antibacterial activities in bothmethods. however, stalk extracts sho wed a lower degree of antibacterial activity than the rootand leaves extracts. generally, the extracts showed a broad spectrum of activity, although theywere more effective against p aeruginosa and proteus spp . in comparison with the positivecontro l. the results suggested that extracts of rheum ribes could be effectively used againstclinical isolates.