General experimental procedures- Ethyl acetate (Scharlau, Spain), methanol ((Scharlau, Spain), n-hexane (Daejung Chemicals and Metals Company Ltd, Korea), peptone (Qualikans, India), yeast (Qualikans, India), agar (Merck, Germany), H2SO4 (Merck, Germany), BaCl2.H2O (Merck, Germany), sterile filter paper disk (BioMaxima S.A., Poland), filter paper (Whatman Int. Ltd, Maid Stone, England), heavy-duty blender (Havells, India) and 13 standard antibiotics (HiMedia, India) were bought from local suppliers. Sterilization, aseptic works and solvent evaporation were done using vertical autoclave machine (Model: LVA-202, Labocon, UK), horizontal laminar airflow cabinet (Model: LLFH-204, Labocon, UK) and rotary evaporator (Model: HS-2005S-N, Hahnshin S&T Co., Ltd, Korea). All used solvents were either analytical grade or distilled prior to use. Medicinal plants- 50 fresh medicinal plants were collected through an expedition from Mirzapur under Tangali, Chattogram and Rajshahi districts. These plants (about 1 kg each) were collected in plastic bags. The plant parts (leaf and stem) were washed with running tap water, cut into small species and dried under shade for 2 weeks in the biological science lab, BOU. After drying, the plant materials were grinded into fine powdered form by using a blender, kept in plastic bags and subjected later to extraction. 10 out of 50 medicinal plants were subjected to activity screening in this research against multidrug-resistant pathogenic bacteria. Extraction of medicinal plants- The powdered form of each medicinal plant (100 g) was taken in 2 L conical flasks and 1 L ethyl acetate solvent was added to it and was left for overnight. Then the plant material was removed by filtration using Whatman filter paper and the filtrate was concentrated to dryness using rotary evaporator at reduced temperature (40°C). After drying, each plant material was extracted again with methanol, filtered and concentrated to dryness as ethyl acetate extract. Both ethyl acetate and methanol extracts were partitioned between methanol and n-hexane; the n-hexane phase mainly contains fats were discarded and the methanol phase was concentrated to dryness using a rotary evaporator at reduced temperature (40°C). These methanol extracts were subjected to activity screening against drug-resistant clinical isolates. Collection of test pathogens- Three multidrug-resistant test pathogens (namely Pseudomonas aeruginosa, Escherichia coli and Klebsiella sp.) were collected from the microbiology laboratory, Rajshahi Medical College, Rajshahi, Bangladesh. These test pathogens were isolated from the clinical samples of the patients. Preparation of the suspension (inoculums) of the test pathogens- To prepare the suspension of the test pathogens, first the test pathogens were streaked on the sterile nutrient agar medium (5 g peptone, 3 g yeast extract, 15 g agar and 5 g NaCl and distilled water 1L) from stock culture and then incubated at 30°C for 24 hours. Then 50 ml nutrient broth medium (5 g peptone, 3 g yeast extract, and 5 g NaCl and distilled water 1L) was prepared, sterilized and inoculated from 24-hour test pathogen cultures and then incubated at 30°C for 24 hours. This culture suspension was used for activity screening of medicinal plant extracts. All the microbial culture works were done under aseptic conditions. Antibacterial activity assay- Antibacterial activity of the solvent extracts was determined by the agar disk diffusion assay method (NCCLS 1993). At first, the suspension of the 24-hour test pathogen culture was diluted with sterilized distilled water in such a way that its turbidity matched with the turbidity of the 0.5 McFarland reagent [A 0.5 McFarland standard was prepared by mixing 0.05 ml of 1.175% barium chloride dihydrate (BaCl2.2H2O), with 9.95 ml of 1% sulfuric acid (H2SO4)]. 0.5 McFarland reagent represents 1.5x108 (generally, range is 1.0x108 to 2.0 x108) bacteria/ml. To prepare the activity assay plate, a nutrient agar medium was prepared (see above) and sterilized at 121°C for 20 min by autoclave machine. The medium was poured on the sterilized Petri dish (90 mm) and left to solidification in a laminar airflow cabinet. Inoculum containing of each bacterial culture to be tested was spread on nutrient agar plates with a sterile swab moistened with the bacterial suspension. Each medicinal plant extract was dissolved and diluted with the appropriate solvent combination. From the diluted each test extract, a specific amount of sample was taken out by the micropipette so that it contained 1 mg extract and impregnated in the sterile microbial susceptibility testing paper disk (6 mm). After drying, all the disks containing test samples were transferred about 2 cm apart by sterile forceps on the surface of the previous test pathogen spread agar plate. These plates were kept in a deep fridge overnight for diffusing extracts in the surrounding media. Then all the test plates were incubated at 30°C for 24 hours. After incubation, the zone of growth inhibition for each extract was measured in mm. 13 different standard antibiotic disks and one sterile microbial susceptibility testing paper disk (6 mm) were used as positive (standard) and negative controls in this experiment, respectively.