الفهرس 
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Abstract
SOS is a bacterial stress response that aids the cell to overcome
DNA damage. The SOS response is triggered by the accumulation of
ssDNA, when cells try to replicate damaged DNA, after UV irradiation,
treatment with antibiotics (fluoroquinolones, β-lactams or mitomycin C)
or any other DNA damaging chemical. The problem of antimicrobial
resistance in bacterial pathogens has been fairly described as a growing
global crisis which has an established link with SOS response. Several
commonly used antibiotics induce the SOS response, potentially
hastening genetic change and the evolution to resistance of pathogenic
populations.
In the current work, the SOS response inducibility in different E.
coli isolates was studied by testing for some SOS parameters as
filamentous growth, RecA protein expression and prophage
inducibility.The antimicrobial sensitivity of isolates for some commonly
used antibiotics and biocides were tested and resistance profiles were
made.
The effect of SOS response on some of resistance development
related processes in bacteria as mutation, transformation and genetic
conjugal transfer was also studied trying to explore the link between SOS
response and antimicrobial resistance.
Results showed high resistance level to nine tested antibiotics:
resistance to cefuroxime (66%) followed by tetracycline, ampicillin,
rifampicin, gentamicin, ciprofloxacin, chloramphenicol and cefotaxime in
percentages of 54.5%, 47.8%, 26.6%, 19.3%, 8.5%, 7.8% and 7.2%
respectively; while imipenem showed the highest antibacterial effect with
resistance percentage of 6.6%. Four isolates were found to be susceptible to all tested antibiotics and only one isolate was resistant to all tested
antibiotics. The remaining isolates showed resistance to one or more
antibiotics, thus 57, 44, 29, 4, 15, 5, 5, and one isolate, were resistant to
one, two, three, four, five, six, seven, and eight antibiotics, respectively.