الفهرس 
Bacterial infections of skin and burn contaminantsOnly 14 pages are availabe for public view
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Abstract
In this study; eighty bacterial isolates identified as E. coli (n=5), K. pneumoniae (n=12), P. aeruginosa (n=23), S. aureus (n=36) and other Staphylococcus sp. (n=4) were recovered from burn infections and other skin or wound infections including; Impetigo and fistulae wounds. The isolated bacteria showed an observable high degree of antimicrobial resistance to several antibiotics specially; Ampicillin, Carbenicillin, Amoxicillin/Clavulanic acid, Cefotaxime and Cefepime while, Imipenem, Levofloxacin and Vancomycin were found to be relatively more effective against most of tested isolates. Generally, up to 91.3% of the tested isolates were found to be MDR. Two metal nanoparticles; silver (Ag-NPs) and zinc oxide (ZnONPs) were synthesized by the chemical reduction and chemical precipitation methods, respectively. Single well separated nanoparticles of average size 12.65 nm for Ag-NPs and 7.6 nm for ZnO-NPs were obtained. Both nanoparticles were examined by UVVis spectrophotometer, EDAX and TEM for their characterization. The efficiency of these nanoparticles as antibacterial agents was determined in-vitro using agar well diffusion method. The obtained results revealed that; these nanoparticles showed a considerable antibacterial activity towards certain Gram positive and Gram negative bacteria even at very low concentration (1mM). However, Ag-NPs were found to be more effective than ZnO-NPs where; twenty four isolates with inhibition zone diameters up to 24mm were obtained with Ag-NPs compared to only nine isolates showed sensitivity to ZnO-NPs with inhibition zone diameters ranging between 11-15 mm. The possibility of using the prepared nanoparticles for enhancing the antibacterial activities of many antibiotics was further studied using disc diffusion method. It was found that, the combination of certain antibiotics with Ag-NPs greatly increased the antibacterial activity of those antibiotics as indicated by observable increasing in the diameters of obtained inhibition zones and consequently, increasing the sensitivity of bacteria to tested antibiotics. For the combination of antibiotics with ZnO-NPs; it was found that the combination was effective with just fewer number of antibiotics such as Amoxicillin/Clavulanic acid and Cefotaxime. Additionally, the current study proved that the combination of certain antibiotics with Ag-NPs not only enhanced their activity against MDR isolates but also greatly decreased their MICs by up to 8 fold. Regarding to the observable obtained in-vitro antibacterial activity of Ag-NPs; the in-vivo application of these nanoparticles within certain pharmaceutical formulations in the treatment of burns contaminated with Pseudomonal infection was also carried out. Five drug formulations; Ag-NPs gel, Neomycin gel, Neomycin – Ag-NPs combination gel, Neomycin – Ag-NPs combination spray and Placebo base gel were prepared and applied for the treatment of fullthickness third-degree bacterially contaminated burns induced in experimental animals (male Swiss albino mice). The results showed that; the maximum healing activity along with the faster wound contraction and retaining most skin normal features was recorded by the treatment with Neomycin – Ag-NPs combination in spray formula followed by the treatment with the same combination in gel formula. Lower healing activity was recorded with the treatment by Ag-NPs gel alone. On the other hand, the treatment with Neomycin gel alone or Placebo gel was found to be ineffective and consequently resulted in massive damage and inflammation to the internal skin layers. Trials for determining the mechanism of antibacterial activity of Ag-NPs and/or their combination with Neomycin compared to the effect of Neomycin alone were also conducted. As observed by the TEM investigations for studying the possible effects of Ag-NPs on bacterial cell morphology and ultra-structure; it was found that Ag- NPs caused great damage in bacterial cell wall and cell membranes affecting their permeability specially when combined with Neomycin. The damaging effects of both agents together on the tested P. aeruginosa cells exceeded that caused by each agent separately. Furthermore, the bacterial cell wall lysis resulted in increasing the amount of proteins and reducing sugars leaked from the cells. The maximum leaked reducing sugars (0.129 mg/ml) and proteins (0.611 mg/ml) were recorded after 24 h of the combining treatment with Neomycin and Ag-NPs. In conclusion, the unique properties of Ag-NPs led to increase their antibacterial activity even against MDR bacteria. In addition, the prepared Ag-NPs were able to enhance the efficiency of certain antibiotics for restoring their activity against the tested MDR bacteria with a lower dose needed which might reduce the side effects of these drugs upon use. The combination of Ag-NPs with Neomycin for the treatment of burns with Pseudomonal infection induced in experimental mice was very effective with great healing activity, rapid wound closure, decreasing in bacterial growth within the site of burns and leaving no scars with almost normal looking of skin features and normal hair growth.