الفهرس | Only 14 pages are availabe for public view |
Abstract The study was conducted to determine the capacity of crude plant extracts to inhibit the growth of E.coli O157 and E.coli clinical isolates. A total of 14 plant extracts were screened for their antimicrobial activity against E.coli O157 using agar diffusion method. Out of 14 plant extracts included in this study, 12 were proved to be potentially active against E.coli O157.These extracts were Eruca sativa, Allium kurrat, Raphanus sativus. L, Punica granatum, Allium cepa, Petroselinum crispum, Anethum graveolinus L, Apium graveolens , Ruta graveolence L., Eugenia aromatica L., Cinnamon zeylanicum Nees and Brassica oleracca where they exhibited zones of inhibitions ranged 18 mm to 21 mm in diameter, compared to zones of inhibitions of common anti-Escherichia coli O157 antibiotics Azithromycin, Norfloxacin, Levofloxacin, Ciprofloxacin which ranged from 18 to 30 mm in diameter. To evaluate the anti- Escherichia coli O157 activity of the plant extracts, MICs of the tested plant extracts against culture of E. coli O157 were determined by agar dilution method. The data obtained showed that the plant extracts of Eruca sativa, Allium kurrat exhibited the highest anti- Escherichia coli O157 activity where their MICs values were≤ 2. 5mg/ml. Moderate antibacterial activity against E. coli O157 was exerted by the extract of Raphanus sativus L, Punica granatum, Allium cepa, Petroselinum crispum, Anethum graveolinus L and Apium graveolens with MIC values ≤5mg/ml. On the other hand, the lowest antibacterial activity against E. coli O157 was shown by Ruta graveolence L., Eugenia aromatica L., Cinnamon zeylanicum Nees and Brassica oleracca extracts, where their MIC values were 10 mg/ml. The antibacterial activity against E. coli O157 of selected antibiotics was also determined; MICs of selected antibiotics against E. coli O157 were determined by microplate assay. Ciprofloxacin, Levofloxacin and Norfloxacin exhibited the highest antibacterial activity against E. coli O157 where their MICs values were ≤ 1.56 µg /ml. On the other hand, a poor antibacterial activity against E. coli O157 was shown by Azithromycin, where its MIC value was 7.5 µg /ml. |