الفهرس 
Introduction and aim of the workOnly 14 pages are availabe for public view
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Abstract
As the problem of global antibiotic resistance continues to worsen, aminoglycosides have assumed increasing importance in clinical practice. However, as with other drugs, their overuse and misuse leads to the development of resistance in important microbial pathogens. In this study, a total of 175 (70%) gram-negative bacterial isolates were recovered from 250 clinical specimens obtained from patients attending El-Minia university hospital . The patients were suffering from different infectious diseases. Escherichia coli was the most prevalent organism of the total isolated bacteria (50/175, 28.5%). Resistance of the isolated bacteria to aminoglycosides was studied. The studied bacteria showed variable degrees of resistance against aminoglycosides. The highest resistance was against streptomycin (82.8%), while the least resistance was against amikacin (17.8%). The different patterns or phenotypes of aminoglycoside resistance as well as the corresponding mechanisms or modifying enzymes were determined using interpretative reading. the different isolates exhibited different phenotypes, the most prevalent of them was ” S” phenotype either alone or in combination in a complex phenotype. Mechanisms of resistance including the production of aminoglycoside modifying enzymes and efflux were determined using pseudomonas aeruginosa isolates. The results showed that the tested resistant pseudomonas aeruginosa isolates exhibited these two mechanisms of resistance. Combinations of some aminoglycosides with some β-lactams or quinolones were evaluated using checkerboard titration method using fifteen E. coli isolates, the most effective combination was amikacin with ciprofloxacin while the least effective combination was gentamicin with amoxycillin.