Quercus infectoria Oliv.

Bacterial resistance to antibiotics is enhanced by unrestricted use of such drugs. In addition, stimulating effects of certain antibiotics on the production of verocytotoxin by enterohemorrhagic Escherichia coli have been reported. The aim of this communication was to report a medicinal plant species that is effective against a broad range of bacteria of clinical importance including Acinetobacter baumannii, Bacillus cereus, Enterobacter faecalis, Escherichia coli, Helicobacter pylori, Klebsiella pneumoniae, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella spp., Shigella flexneri, Staphylococcus aureus, Streptococcus mutans, and Streptococcus pyogenes. Ethanol extracts of Quercus infectoria Oliv. (Fagaceae) demonstrate a broad spectrum of activity against all bacterial species tested. Detailed studies were carried out on clinical isolates of pathogens commonly presenting problems with the use of antibiotics, including enterohemorrhagic Escherichia coli (EHEC), methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Klebsiella pneumoniae, multidrug-resistant Helicobacter pylori, and Salmonellaspp. The extracts of Quercus infectoria displayed remarkable activity against MRSA with MICs ranging from 0.02 to 0.4 mg/mL, and MBCs ranging from 0.4 to 1.6 mg/mL. More importantly, this plant species could exhibit strong antibacterial activity against all Gram-Negative organisms. Its significant activity was shown with EHEC, with MICs of 0.05 to 0.1 mg/mL and MBCs of 0.8 to 1.6 mg/mL. The results from this study indicate that Quercus infectoria is potentially a good source of antibacterial substances with broad spectrum of activities against antibiotic-resistant bacteria.