الفهرس 
I. INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Microorganisms are responsible for wound infection; widespread controversy still exists regarding the exact mechanisms by which they cause infection and also their significance in non healing wounds that do not exhibit clinical signs of infection. One school of thought is that the density of microorganisms is the critical factor in determining whether a wound is likely to heal. However, a second school of thought argues that the presence of specific pathogens is of primary importance in delayed healing, while yet others have reported microorganisms to be of minimal importance in delayed healing (Bowler et al., 2001).
P. aeruginosa is a pathogenic rod –shaped Gram negative bacteria which can be isolated from several infected tissues, it is an opportunistic organism which only infect immune-compromised patients. It can survive on moisture corners, walls and floors of hospitals (Arora et al., 2011).
P. aeruginosa is the main cause of several severe infectious diseases such as UTI (Urinary tract infection), CF (Cystic fibrosis), and also wound and burn infection. To define a pathogenic organism as MDR- Organism, it must be resistant to one of the antibacterial agents of (carbapenems, fluroquinolones and aminoglycosides) (Magiorakos , 2011).The threat of MDR- P. aeruginosa had been increased and become intensively studied by the scientists everywhere as P. aeruginosa acquired resistance against most of the recent used antibacterial agents(Antibiotics) (Gad et al., 2007).P. aeruginosa enhance its resistance through several mechanisms such as efflux pumps, or it can form biofilms, it can produce several enzymes which can inhibit the activity of some antimicrobial agents like β-lactam it produce β-lactamase and aminoglycosides it produce aminoglycoside modified enzymes (Carmeli , 2002).
Antibiotics used to treat P.aeruginosa infections include a number of β-lactams such as cephalosporins (e.g. ceftazidime), carbapenems (e.g. imipenem, meropenem) and monobactams (e.g. aztreonam). Piperacillin is a penicillin class β-lactam that remains effective in treating most P.aeruginosa clinical infections. Other major classes of antibiotics used to treat P.aeruginosa infections include aminoglycosides (e.g. gentamicin, tobramycin, amikacin), quinolones (e.g. ciprofloxacin), and, more recently, polymyxins (e.g. colistin, polymyxin B). Separate multi-drug resistant strains of P.aeruginosa isolated from clinical environments display a high degree of variability in acquired mutations that lead to resistance suggesting that resistance can develop readily and rapidly (Jeukens et al., 2014). Here the major mechanisms of antibiotic resistance in P. aeruginosa that fall under the classifications of intrinsic, acquired and adaptive resistance will be discussed.
The low permeability of P. aeruginosa outer membrane serves as a significant barrier to the penetration of antibiotics and therefore, small hydrophilic antibiotics, such as β-lactams and quinolones, pass through the water-filled porin channels relatively slowly, making Pseudomonas generally more intrinsically resistant to most antibiotics. Nevertheless, although low outer membrane permeability such regulators (Yeung et al., 2009) identified 18 such “switch” regulators suggesting that there are multiple systems that regulate biofilm development.
Essential oils have been shown to possess antibacterial, antifungal, antiviral insecticidal and antioxidant properties. Some oils have been used in cancer treatment. Some other oils have been used in food preservation, aromatherapy and fragrance industries. Essential oils are a rich source of biologically active compounds. There has been an increased interest in looking at antimicrobial properties of extracts from aromatic plants particularly essential oils .Therefore, it is reasonable to expect a variety of plant compounds in these oils with specific as well as general antimicrobial activity and antibiotic potential (Burt, 2004).
Hydrogels are three-dimensional, cross-linked networks of water-soluble polymers. Hydrogels can be made from virtually any water-soluble polymer, encompassing a wide range of chemical compositions and bulk physical properties. Further-more, hydrogels can be formulated in a variety of physical forms, including slabs, microparticles, nanoparticles, coatings, and films. As a result, hydrogels are commonly used in clinical practice and experimental medicine for a wide range of applications, including tissue engineering and regenerative medicine, diagnostics, cellular immobilization, separation of biomolecules or cells, and barrier materials to regulate biological adhesions (Cho et al., 2003).
In this study, therefore, cinnamon oil, chitosan, honey and gelatin were selected to prepare hydrogel shets as wound dressings. The properties of the hydrogel sheet, such as antibacterial activity, non-toxicity and wound healing, were investigated.