Expression of DNA Gyrase at mRNA Levels and Antibacterial Effect of FluoroquinoloneDerived Compounds on Two Antibiotic Resistant Bacteria; Staphylococcus aureus and Enterococcus faecalis

Abstract

Introduction: Fluoroquinolones are a form of antibiotics capable of influencing DNA Gyrase of bacteria. Any alteration in the structure of current fluoroquinolone antibacterials may provide a better effect on the growth inhibition of bacteria. Aim: To assess the probable anti-bacterial activity of two fluoroquinolone derivatives on Staphylococcus aureus (S.aureus) and Enterococcus faecalis (E. faecalis). Materials and Methods: The inhibitory effect of two synthetic derivatives of fluoroquinolones, N-4-methyl (phenyl) -2,2,2- trifluoroacetimidoyl ciprofloxacin (C1), and N-4-methyl (phenyl) -2,2,2-trifluoroacetimidoyl norfloxacin (C2), was measured by Minimum Inhibitory Concentration (MIC) using Broth Microdilution (BMD) and disc diffusion methods. Also, by using real-time PCR technique, the influence of C1/C2 was evaluated on DNA gyrase gene expression of S.aureus and E. faecalis and all compared with vancomycin as a control antibiotic. Collected data were analysed by SPSS 18.0 software. One-way ANOVA and Tukey’s multiple comparisons test were used for it. Results: The findings showed that vancomycin (MIC, 16 µg/mL) has higher antimicrobial activity, especially on E. faecalis, compared to C1 (MIC, 256 µg/mL). The anti-bacterial effect of C2 (MIC, 128 µg/mL) was higher on E. faecalis but no significant effect on S. aureus. (p<0.05). In addition, the results of gene expression alterations showed that the C1 reduced the gene expression of DNA gyrase in tested bacteria, but not significant in comparison to control (p<0.05). C2 reduced the gene expression of DNA gyrase in both bacteria and it was significant for E. faecalis (p<0.01). Conclusion: Because of bacterial growth inhibition characteristic, C2 possibly may be used as an alternative antibiotic to control infection caused by E. faecalis.

Keywords

• bacterial infections
• drug resistance
• synthetic drug