Abstract
The present work aims to examine the antimicrobial activity of three medicinal plant extracts grown in Saudi Arabia namely Pulicaria crispa, Achillea fragrantissima and Cleome Africana against 10 clinical isolates of multi-drug resistant bacteria (MDR) that belong to four species, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumonia. The antibacterial potential of the methanolic plant extracts was assessed by the agar well diffusion method and expressed in terms of diameters of inhibition zone. The outcomes of these experiments indicated that each extract has shown an activity against four resistant isolates at least, with maximum zone of inhibition 19 mm recorded by P. crispa extract against S. aureusstrain (1). As a new finding, it was observed that C. Africana extract has bioactivity as antibacterial agent against maximum number of resistant isolates (seven out of ten tested strains) including all tested isolates of S. aureus (ranged between 7 and 14 mm). Methanolic extract of A. fragrantissima demonstrated two considerable growth inhibition against one isolate of both S. aureus and Ps. aeruginosa. The chemical analysis of the three plants extracts was carried out using Gas Chromatography-Mass Spectrometry instrument (GC-MS). The results showed the presence of many active groups of phytochemicals such as Flavonoids, Glycerides, Tannins, Alkaloids and Steroids. The good activity of medicinal plants was originated from presence of these compounds.