Molecular study on resistance of clinical isolates from wounds and burns sepsis to silver nanoparticles synthesized by gamma radiation / Dina Abdelaleem Soliman Aboulmagd ; Supervised Salwa Abdelmoneim Rasmy , Alaa Eldien Mahmoud Shawky Hosny , Zeinab Eldemerdash Mohamed Elbazza

Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

The widespread use of silver-containing compounds has led to emergence of silver-resistant bacteria. Different clinical isolates were obtained from burns and wounds and identified using the biochemical tests and API method. Their susceptibility was tested by both the disk diffusion and broth microdilution methods, while their MIC against AgNO3 was determined using the broth macrodilution method. The presence of different sil genes on the extracted plasmids and their replicon types were investigated using PCR. The ability of these plasmids, to impart silver-resistance, was tested by transformation. AgNPs are promising antimicrobial agents for treatment of wounds and burns. They were synthesized using honey at different pH values or with different gamma irradiation doses.They were characterized by Ultraviolet-Visible spectroscopy, Transmission electron microscope, Dynamic light scattering and Fourier transform-infrared and their antimicrobial activity was evaluated by MIC determination. The collected isolates were MDR and 19 silver-resistant bacterial isolates (12.6%) were detected; with AgNO3 MIC {u2265}512 æg/ml. PCR revealed the presence of sil genes on the extracted plasmids. These plasmids were capable of transferring the same level of silver-resistance to recipient cells. The extracted plasmids had different replicon types. AgNPs prepared using 30g of honey at 5 kGy had the best physical characters and recorded the lowest MIC values. In conclusion, plasmid-mediated silver-resistance was detected, for the first time, in clinical P. aeruginosa, A. baumannii and S. aureus isolates; in addition to its detection in K. pneumoniae, E. coli and Enterobacter cloacae. Also, honey and gamma radiation can be used in synthesis of highly stable pure AgNPs. This offered an advantage in terms of inhibition of silver-resistant bacteria isolates

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