الفهرس 
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Abstract
Abstract
Hospitalizations play a major role in the management of acute illnesses, and they also enhance the risk of susceptible patients for multiple nosocomial and often antimicrobial-resistant pathogens. The use of plant extracts in the treatment of many pathogenic bacteria is promising.In this work we showed antibacterial activity of some plant extracts against human pathogenic bacteria. Four bacterial isolates were isolated from Egypt. These isolates were identified biochemically and by means of 16s rRNA gene typing and were designated as Acinetobacter baumannii complex 212S, Pseudomonas aeruginosa 252A, Proteus mirabilis 210P and Klebsiella pneumonia 4010S. Antibiotic susceptibility test showed resistance of isolates to at least ten antibiotics.
In vitro investigations of nine Egyptian plant extracts, identified that ethanolic pomegarante peel and ethanolic moringa olifera seeds extracts to exhibit antibacterial activity against human pathogenic isolates. Inhibition zone of 22.333±0.58, 21.000±1.0, 19.333±0.58 and 20.333±0.58 mm was detected when pomegranate peel extract applied against above mentioned bacteria respectively. While inhibition zone of 13.333±0.58, 10.667±0.58, 11.333±1.15 and 12.000±1.0 mm was detected by moringa olifera seeds extract. Ethanolic pomegranate peel and ethanolic moringa olifera seeds extracts exhibit bacteriostatic and bactericidal against all strains with MICs/MBCs ranging between 37-100 mg/L for ethanolic pomegranate peel 40-135 mg/L for ethanolic moringa olifera seeds extracts.
All these isolates were killed after 4 and 6 h upon grow with 100 mg/L respectively. Additionally, gas chromatography-mass spectrometry GC/MS profiling identified and detected a variable number of antimicrobial compounds in both extracts. Pomegranate peel and moringa olifera seeds were exposed as powder to various doses of gamma irradiation range from (1.0:5.0) kGy and then prepared extracts, irradiated ethanolic pomegranate peel and moringa olifera seeds extracts to exhibit antibacterial activity against human pathogenic isolates. Inhibition zone of 20.0±0, 25.667±0.58, 31.333±1.15 and 13.667±1.15 mm were detected when pomegranate peel extract applied against above mentioned bacteria respectively.While inhibition zone of 16.333±0.58, 16.333±0.58, 15.667±0.58and 16.000 ±1.0 mm were detected by moringa olifera seeds extract .
Scanning Electron Microscopy (SEM) images showed the morphological damages and strong destructive effects against gram-negative bacteria. using quantitative real-time PCR to illustrate the effect of ethanolic medicinal plant extracts on virulence associated genes expression VanA, VanB , mecA and Blaz gene .The results showed that there is significantly down regulation in gene expression in bacteria reated with plant extracts.