Evolution of Antimicrobial Activity of Leaf Extract of Withania somnifera Against Antibiotic Resistanct Staphylococcus aureus

Background: Emergence of bacterial resistance is critically an alarming situation in the health care industries. The medicinal plants have been used in the folk medicine to treat diseases without knowing their active compounds. Objectives: The aim of present study was to screening the antibacterial activities of Withania somnifera leaf extract against antibiotic resistant strains of Staphylococcus aureus. Patients and Methods: In this cross-sectional study, a total of 17 strains of S. aureus were isolated from hospitalized patients (Boo-Ali, Nabi-Akram and Imam-Ali hospitals, Zahedan, South-Eastern Iran) suffering from urinary tract infections during the years 2011 - 2012. The extract of W. somnifera obtained by rotary and the minimum inhibitory concentrations were investigated to characterize the antimicrobial activities of this extract. Results: Overall, S. aureus showed resistance to 6 antibiotics including oxacillin (83.3%), ceftazidime (66.6%), penicillin (50%), trimethoprim-sulfamethoxazol (41.6%), cefixime (33.3%) and vancomycin (8.3%). The highest minimum inhibitory concentrations (MIC) values of extract were found to be 250 ppm against 12 strains and the least value was 63 ppm against 2 strains. Conclusions: Ethanol extract of W. somnifera leaf might be exploited as natural drug for the treatment of several infectious diseases caused by this pathogen.