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

Antimicrobial drug resistance has become an emerging threat and a matter of concern worldwide. Many steps are being taken to reduce this problem, like gradually limiting antibiotics administration against pathogenic bacteria and searching for non-antibiotic compounds that have antibacterial activity through different mechanisms. The aim of this work was to evaluate the antibacterial effect of diclofenac sodium on enterococcal growth, ciprofloxacin resistance and biofilm forming ability. The effect of exposure of enterococcal isolates to diclofenac sodium on their expression of efflux pump genes (efrA and efrB) and adherence-related genes (asa1 and efaA) was also investigated. Fifty Enterococcal isolates were retrieved from 36 urine and 14 pus specimens. Antimicrobial activity of diclofenac and ciprofloxacin was determined by agar dilution method.Their effect on biofilm formation was determined by tissue culture plate method. The expression of asa1, efaA, efrA and efrB genes was determined by RT-PCR before and after exposure to diclofenac. Ciprofloxacin resistance was reported in 54% of the enterococcal isolates. Diclofenac was found to have antibacterial activity, as it inhibited the growth of enterococcal isolates at MIC of 400-800æg/ml. Although diclofenac induced a statistically significant reduction in the expression of efflux pump genes (efrA and efrB) (P < 0.001), it failed to reduce either ciprofloxacin resistance rate or ciprofloxacin MICs. Biofilm formation was reported in 64% of the isolates

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