|Iranian Journal of Pharmaceutical Research
(2009), 8 (4): 293-300
Received: May 2008
Accepted: January 2009
Copyright ? 2009 by School of Pharmacy
Activity of Some Plant
Multi-Drug Resistant Human Pathogens
Mustafa Oskay*, Dilek Oskay and Fatih Kalyoncu
Department of Biology, Faculty of Sciences and Arts, Celal Bayar University, Campus of Muradiye, Manisa, Turkey.
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.
One of the more alarming recent trends in infectious diseases has been the increasing frequency of antimicrobial resistance among microbial pathogens causing nosocomial and community-acquired infections. Numerous classes of antimicrobial agents have become less effective as a result of the emergence of antimicrobial resistance, often as a result of the selective pressure of antimicrobial usage. Among the more important emerging resistance problems are oxacillin resistance in staphylococci, penicillin resistance in streptococci, vancomycin resistance in enterococci (and eventually staphylococci), resistance to extended-spectrum cephalosporins and fluoroquinolones in Enterobacteriaceae, and carbapenem resistance in P. aeruginosa (1). For example, in clinical isolates of S. pneumoniae resistance to antibiotics routinely used to treat infections is now at 40% in some European countries. Similarly, a high level of ampicillin resistance is very significant in E. coli, while it would be natural in most other enterobacteria. Escherichia coli and Klebsiella spp. are the only ones generally susceptible to narrow-spectrum cephalosporins (2). Also, MRSA, gained much attention in the last decade, is a major cause of hospital-acquired infections (3). During the last two decades a renewed interest in Corynebacterium species and other non-spore-forming Gram-positive bacilli has emerged among clinicians and microbiologists alike. Infections caused by these organisms are emerging, new species are being recognized, and infections by toxigenic and nontoxigenic Corynebacterium diphtheriae strains are also being described with increasing frequency, indeed, in countries where diphtheria had been totally or almost eradicated (4).
Herbal medicines have been important sources of products for the developing countries in treating common infectious diseases and overcome the problems of resistance and side effects of the currently available antimicrobial agents (5). The World Health Organisation (WHO) estimates that 80% of the people living in developing countries almost exclusively use traditional medicines. This means approximately 3300 million people use medicinal plants on a regular basis. Medicinal plants used in traditional medicine should therefore be studied for safety and efficacy (6).
Using plants for medicinal purposes is an important part of the culture and the tradition in Turkey. Therefore, this in vitro study was aimed at screening selected plants for their antibacterial activity and evaluating their potential use in treating infections caused by multi-drug resistant clinical bacteria.
Plant materials and preparation of the ethanolic extracts
Plants were collected in different sites of Manisa province and arounds of Turkey. Voucher specimens were deposited in the Herbarium of Botany, Department of Biology, Celal Bayar University. The used parts were leaves, stems, flowers, roots, young branches and, in some cases, fruits (Table 1).
The plant parts were separated, washed with distilled water, dried and then powdered finely using a blender. Thirty grams of ground air-dried plant material were shaken in 150 mL 96% weight/volume (w/v) ethanol (EtOH 96?) at room temperature for 60 h (180 cycles/min). The insoluble material was filtered by filter paper (Whatman No. 4) and evaporated to dryness in a water bath at 50?C. The extract was weighed and dissolved in EtOH 96? at a concentration of 200 mg/mL and stored at +4?C for further experiments.
Clinical isolates of the following: bacteria MRSA (Penicillin G- and oxacillin-resistant, and clindamycin-, vancomycin-, erythromycin-, sulfamethoxazole- and teicoplanin-sensitive), E. coli (Ampicillin-, amoxycillin- and sulfamethoxazole-resistant, and gentamicin-, cefuroxime-, levofloxacin-, imipenem-, aztreonam- and netilmycin-sensitive), P. aeruginosa (