antibacterial activity of various plants extracts against antibiotic-resistant aeromonas hydrophila

background aeromonas hydrophila cause one of the most important diseases in fishes and lead to economic losses, and may be contaminated human beings. objectives the current research aimed to investigate the anti-bacterial activity shown by the extracts prepared from different parts of olea europea, myrtus communis, thymus vulgaris, rosmarinuis officinalis, and achillea falcata that grow in syria against a. hydrophila that causes the most dangerous bacterial diseases in fish. materials and methods the study was performed in four stages: first of all, the presence of a. hydrophila was investigated in 450 samples of cyprinus carpio fish using blood agar, trypticase soya agar, and analytical profile index (api20e). secondly, the plants extract was obtained using water, absolute alcohol, then ether using soxhlet extraction apparatus and rotary vacuum evaporator. thirdly, the antibacterial activity of some antibiotics on these bacteria was evaluated by disk diffusion method. finally, the antibacterial effect of the extracts was determined by disk diffusion method. results the studied antibiotics showed no antibacterial activity against these bacteria, except amikacin which had an acceptable effectiveness. however, the ethanol extracts of the studied plants revealed different antibacterial effects against a. hydrophila which showed antibiotic resistant. t. vulgaris extract had the strongest effect, whereas o. europea extract had the weakest activity. the water and ether petroleum extracts had no antibacterial activities. conclusions ethanol extracts of the studied plants had different antibacterial effects against antibiotic-resistant a. hydrophila. t. vulgaris had the highest activity, r. officinalis had the second, and m. communis and a. falcate were in the third place, while the o. europea had the weakest antibacterial activity.