Activity of Some Plant Extracts AgainstMulti-Drug Resistant Human Pathogens

Plants used for traditional medicine contain a wide range of substances which can be used to treat various infectious diseases. Hence, antibacterial activities of ethanolic extracts of 19 plant species were studied against multi-drug resistant clinical isolates using agar well diffusion method. Extracts of Liquidambar orientalis, Vitis vinifera, Rosmarinus officinalis, Punica granatum, Cornus sanguinea, Euphorbia peplus, Ecballium elaterium, Inula viscosa and Liquidambar orientalis showed broad-spectrum antibacterial activity with inhibition zones ranging from 8 to 26 mm. The most resistant organisms were Escherichia coli (E. coli) (Ampicillin-, amoxycillin- and sulfamethoxazole-resistant), Stenotrophomonas maltophilia (S. maltophilia) (Amoxycillin- and nalidixic acid-resistant) and Klebsiella pneumoniae (K. pneumoniae) (Ampicillin-, amoxycillin- and aztreonam-resistant), and the most susceptible species were Staphylococcus aureus (S. aureus) (Penicillin G- and oxacillin-resistant), Streptococcus pyogenes (S. pyogenes) (Penicillin G-, erythromycin- and clindamycin-resistant) and Pseudomonas aeruginosa (P. aeruginosa) (Sulfamethoxazole- and novobiocin-resistant), respectively. Minimum Inhibitory Concentrations (MIC) of crude extracts were determined for the seven highly active plants showing activity against methicillin resistant S. aureus (MRSA), E. coli, P. aeruginosa, S. pneumoniae and the reference bacteria (E. coli ATCC 11229 and Kocuria rhizophila ATCC 9341 NA). MICs of active extracts ranged from 8 to 14.2 mg/mL against one or other test bacteria.