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Evidence-Based Complementary and Alternative Medicine
Volume 2016, Article ID 7083964, 5 pages
Research Article

Antibacterial Activity of Salvadora persica L. (Miswak) Extracts against Multidrug Resistant Bacterial Clinical Isolates

1Department of Pediatrics, College of Medicine, Najran University, P.O. Box 1988, Najran, Saudi Arabia
2Microbiology Department, College of Medicine, Najran University, P.O. Box 1988, Najran, Saudi Arabia
3Pharmacognosy Department, College of Pharmacy, Najran University, P.O. Box 1988, Najran, Saudi Arabia
4The Faculty of Sharia and Fundamentals of Religion, Najran University, P.O. Box 1988, Najran, Saudi Arabia

Received 27 September 2015; Revised 22 December 2015; Accepted 28 December 2015

Academic Editor: Kang-Ju Kim

Copyright © 2016 Mohamed Saeed Zayed Al-Ayed et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Much effort has focused on examining the inhibitory effect of Salvadora persica (miswak) on oral microorganisms, but information concerning its antibacterial activity against other human pathogens, particularly multidrug resistant (MDR) isolates, is scarce. Therefore, this study aimed to assess the in vitro antibacterial activities of Salvadora persica L. extracts against 10 MDR bacterial clinical isolates other than oral pathogens. The antibacterial activity of aqueous and methanol miswak extracts was assessed using the agar dilution and minimum inhibitory concentration (MIC) methods. Overall, the 400 mg/mL of miswak extract was the most effective on all strains. The methanol extract exhibited a stronger antibacterial activity against Gram-negative (3.3–13.6 mm) than Gram-positive (1.8–8.3 mm) bacteria. The lowest MIC value was seen for E. coli (0.39, 1.56 µg/mL), followed by Streptococcus pyogenes (1.56 µg/mL). The highest MIC value (6.25, 12.5 µg/mL) was recorded for methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii, and Stenotrophomonas maltophilia. This study demonstrates, for the first time, the moderate to strong antibacterial activity of miswak extracts against all tested MDR-pathogens. Methanol extract appears to be a potent antimicrobial agent that could be considered as complementary and alternative medicine against resistant pathogens. Further studies on a large number of MDR organisms are necessary to investigate and standardize the inhibitory effect of miswak extracts against these emerging pathogens.