الفهرس 
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Abstract
The immune system in the human body performs the process of defending the body against various microbes. People who suffer from immunodeficiency, especially cancer patients, lose the ability to fight these microbes and be a target for them, which may lead to death.
2- A collection of 283 samples from cancer patients were collected from the national cancer institute in Cairo, Egypt, from December 2016 to July 2018, from various sources such as blood, pus, urine, throat, tongue, and ear swab, etc. These samples were grown on different media like MacConkey agar, blood agar, and sabouraud dextrose agar to isolate the present microbes.
3- The isolated microbes were picked and were subjected to purification process and identification by standard microbiological methods (morphology, biochemical, and Vitek -2 system).
4- Results of identification of microbial isolates were revealed that 181 identified bacterial isolates were obtained as the following, Escherichia coli with frequency rate (34.80%), Klebsiella pneumonia (29.82%), Acinetobacter baummannii (13.81%), Pseudomonas sp. (8.83%), Enterobacter sp. (4.41%), Staphylococcus sp. (3.31%), Proteus mirabilis (1.65%). Citrobacter freundii (1.10%), Serratia marcescens (0.55%), Cedecea davisae (0.55%), Burkholderia cepacian (0.55%), Pantoea agglomerans (0.55%), Candida tropicalis (13.06%), Candida kruse (8.11%), candida albicans (7.41%), and Candida glabrata (7.41%). It was found that the number of bacterial isolates from adults was 146 isolates with a percentage of 51.53%, while the number of isolates in children was 35 isolates with a percentage of 12.35%, gram - negative bacteria was represented by 175 isolates represent 61.77% , while the gram-positive bacteria represented by 6 isolates, with
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a rate of 2.11% and candida represented by 102 isolates with a rate of 36.11%, divided as follows :68 isolates of adults, 24.1%, while 34 children were isolated with a rate of 12%.
5- The susceptibility of Gram-negative bacteria to different antibiotics revealed that amikacin, gentamycin, and meropenem were the most effective antibiotics with a ratio of (57.67 %), (38.25%), and (34.26%), while ampicillin, cefazolin ceftriaxone, amoxicillin/sulbactam, trimethoprim/ sulfamethoxazole amoxicillin/clavulanic acid and ceftazidime were the less effective antibiotic with resistance ratio of (97.07%), (95.35%), (90.21%), (87.93%), (86.97%), (85.65%) and (85.65%) respectively.
6-Susceptibility of Staphylococcus sp. to different antibiotics revealed that vancomycin, nitrofurantoin, cefoxitin, meropenem, linezolid, and tigecycline highly effective antibiotics with a susceptibility ratio of 100%. On the other side, this isolate was resistant to oxacillin tetracycline with a ratio of 100%.
7 -Gram-negative producing (ESBL) were detected with the percentage (34.83), (27.79%), (13.70%),(4.56%), (2.85%), (1.71%) and ( 1.14%) as in E.coli, klebsiella pneumonia, Acinetobacter baummannii, pseudomonas sp., Enterobacter sp., Proteus mirabilis and Citrobacter freundii respectively.
8-Susceptibility of all Candida sp. to antifungal compounds revealed that caspofangin and miconazole were the most effective ones with a percentage of 65.66%, 54.88%, and high resistance to fluconazole, Posaconazole, and itraconazole with percentage 77.42%, 68.60%, and 61.74%, respectively.
9- Biosynthesized silver nanoparticles by Aspergillus fumigautes, purification and characterized by high-resolution transmission electron microscopy (TEM), optical and ultraviolet spectroscopy (UV), and X-ray diffraction analysis (XRD) showed
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that the manufactured particles were well dispersed and spherical with a size ranging from 10-100 nanometers.
10- The antimicrobial activity of the silver nanoparticles was tested against the isolates’ most resistant to antibiotic which demonstrated the inhibitory effect of these nanoparticles on the microbes significantly.
11-The cytotoxicity of biosynthesized AgNPs from A. fumigatus (ATCC1922) against HeLa cell line revealed that, HeLa cells viability after treatment with 1, 2, 4, 6, 8, 10, 20 and 40 μg/ml of AgNPs was found to be 96.3, 85.2, 73.1, 64.5, 42.0, 35.2, 24.5 and 15.0%, respectively. The IC50 value of AgNPs was found to be 6.0 μg/ml.
12- Four different amino acids were used to improve the antimicrobial activity, which showed an effect on some types of antibiotics and made them more effective