Antibacterial Activity of Some Plant Extracts on Escherichia coli with Special Reference to its Resistance Pattern

The present work was planned to isolate, characterize and evaluate the prevalence of E. coli serotypes in 180 samples (herbs, water and chicken) as well as detection of haemolysin production, Congo Red binding activity, serum activity and antimicrobial susceptibility test. Forty four samples out of 180 samples were found to be positive to E. coli with a percentage of 24.4%. The serological identification showed that O125, O112 and O86 were the most prevalent serotype among the 44 isolated strains with percentages of 27%, 25% and 18% respectively. The study showed that all 44 E-coli isolates had the ability to bind with C.R. dye gave red colonies and were sensitive to bactericidal effect of human and sheep serum (100%). The results of haemolysis showed that the isolates belonged to O112 and 0114 serotypes had a hemolytic activity and the other serotypes had no hemolytic activity. The result of antibiotics sensitivity indicated that E. coli strains were highly resistant to penicillin and erythromycin (100%), followed by gentamicin, ampicillin, oxytetracycline and nalidixic acid with percentages of 81.8%, 75%, 47.7% and 15.9 %respectively. All E. coli strains were found to be moderately sensitive to ceftazidime (100%) and sensitive to ciprofloxacin (70.5%). The result of ethanolic plant extract showed that Coriander, Ginger, bay leaf, Black pepper, Chilly, Parsley and Turmeric did not show any bactericidal activity against E. coli strains. While Hibiscus, Thyme and Cinnamon showed intermediate bactericidal activity in concentration 100% .Moreover, Black cumin showed low bactericidal activity against herbs and water isolates only with 100% concentration.