Study the expression of rpos gene in a ciprofloxacin medium resistant E.coli mutant

Introduction and Objectives: E. coli is a gram negative bacterium belongs to Enterobacteriacea family. Some of its strains cause urine infection. Ciprofloxacin is a selective treatment against this infection. This antibiotic belongs to the second-generation of fluoroquinolone and its target is A and B subunits of DNA gyrase. Recent studies have shown that ciprofloxacin enhances the expression of recA and recF genes in ciprofloxacin-resistant mutants. recF locates in a four-gene operon and can be expressed by either operon promoter or its own promoter. Special promoter is activated by RpoS sigma factor in stationary phase. Therefore, the aim of this study was to study the expression of rpoS gene in E.coli mutant with intermediate resistance to ciprofloxacin after treatment with this antibiotic. Materials and methods: For determination of relative expression of rpoS, firstly, RNA was extracted and then cDNA was synthesized. Real-time PCR method then was used to determine the gene expression. Results: The result of present study showed that the rpoS gene expression level did not increase at logarithmic phase following treatment with ciprofloxacin. Conclusion: The increase in recF expression after treatment with ciprofloxacin is not related to its own promoter and is relevant to the operon promoter.

کلیدواژه ها:

E.coli ، rpos gene ، Real time PCR ، ciprofloxacin