Abstract

Accumulating data have been dramatically increasing on multiple drug resistantStaphylococcus aureus isolates that are incriminated in nosocomial and community acquired infections causing high mortality and morbidity. Accordingly, 70 resistant isolates were collected from King Fahad General Hospital and National Guard Hospital, Jeddah, Saudi Arabia in an attempt to find alternative antimicrobial substances from various plant extracts.  The susceptibility pattern was as follows:  50 isolates were resistant to fusidic acid, 28 isolates were resistant to oxacillin, 20 isolates were resistant to penicillin, 20 isolates were resistant to clindamycin and 21 isolates were resistant to gentamycin. However, all the isolates were sensitive to vancomycin. The antimicrobial activity of the aqueous extracts of five medicinal plants namely Canellia sinensis (green tea), Punnica granatum (pomegranate rind), Psidium guajava Lim (guava leaves), Cinnamomum verum(cinnamon) and Mourus (raspberry) was tested against the 70 resistant isolates of S. aureus using agar well diffusion assay. Significant difference was noted in the inhibitory effect between most of the tested extracts. Pomegranate rind showed the highest activity, followed by green tea, guava leaves, cinnamon bark and raspberry fruits extract respectively, compared to commercial antibiotics. Interestingly, the inhibitory activity of three combined extracts: green tea, pomegranate rind and guava leaves was found to be higher on 20 clindamycin resistant isolates compared to each extract alone, indicating synergistic interaction. These results emphasize the promising role of plant extracts as alternative antibacterial agents against resistant strains of S. aureus if not other pathogenic bacteria.

 Keywords: Staphylococcus aureus, antimicrobial activity, plant extracts, inhibition, methicillin.