الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
According to World Health Organization (WHO), lower respiratory
tract infections are the third most common cause of death worldwide.
These infections are mainly caused by multidrug-resistant (MDR) bacteria.
Between 8% - 28% of patients receiving mechanical ventilation are
affected by ventilator associated pneumonia (VAP).The causative
microorganisms are extremely resistant rendering the proper choice of
antibiotics for treatment difficult. The drugs which disrupt virulence factors
of bacteria are more promising as the bacteria cannot develop resistance
against them. Quorum sensing inhibitors are used to disrupt intra and inter
bacterial communications giving better chance for host defense
mechanishms.
The aim of current study was to characterize bacteria isolated from
VAP patients, to evaluate the effectiveness of some antimicrobial agents,
characteraize MDR strains, screen isolates for quorum sensing systems and
to evaluate efficacy of different essential oils as quorum sensing inhibitors.
Clinical bacterial isolates were recovered from patients having
pneumonia associated with mechanical ventilation from intensive care units
of Zagazig University Hospital and identified using standard
microbiological methods. The specimens were cultured on nutrient agar,
blood agar, Mac-Conkey agar and mannitol salt agar and incubated for 24
hours at 37°C. Isolated bacteria were characterized using cultural and
biochemical characteristics.
A total of 233 bacterial isolates were recovered from 153
endotracheal aspirate samples, compromising 203(87.1%) Gram negative
and 30 (12.9%) Gram positive isolates. The major isolates were Klebsiellapneumoniae (36.9%), Escherichia coli (21.03%), Acinetobacter baumannii
(14.59%), Pseudomonas aeruginosa (14.16%) and Staphylococcous aureus
(12.02%).