Evaluation of Synergistic Antimicrobial Effect of Ascorbic Acid with Antibiotics Against E. coli O157 In Vitro

Abstract

The present study was carried out to study the interaction between ascorbic acid and two antibiotic (ciprofloxacin and erythromycin) in-vitro and the in vitro. The research was included two experiments. The first one was to isolate and identify E. coli O157; E. coli sample was taken from a hospital, the sample was cultured on MacConkey agar, Sorbitol MacConkey agar, chrome agar, eosin methylene blue agar, then VITEK® 2 System was performed Data showed the sample was positive as a result of E. coli O157. The second experiment examined the pharmacodynamics of ascorbic acid in various states, including alone and in combination with ciprofloxacin and erythromycin. Results showed that the MIC of ascorbic acid (AA), ciprofloxacin (CIP), and erythromycin (ERY) against E. coli O157 was 16 mg/ml, 2 g/ml, and 256 g/ml, respectively, and the values of MBC by utilizing of Time kill curve were 32 mg/ml, 4 g/ml, and 512 g/ml for each of them, respectively. The pharmacodynamics-interactions within double combinations of ascorbic acid (AA) with ciprofloxacin (CIP) and erythromycin (ERY) against E. coli O157 isolate by micro dilution checkerboard assay showed that the combination of ascorbic acid with ciprofloxacin exhibited synergistic antibacterial effects through fractional inhibitory concentration (FIC index < 1) against tested isolate, while the combination of ascorbic acid with erythromycin exhibited antagonistic effects. Furthermore, time-kill analysis showed that ASCORBIC/CIP combination exhibited highest synergistic and bactericidal effect. It was determined that in vitro study against E. coli O157 in the treatment of urinary tract infection, the combination of ascorbic acid and ciprofloxacin was both more potent and safer than the combination of ascorbic acid and erythromycin. From this study concluded the combination of ciprofloxacin, and erythromycin against isolated E. coli showed that this microorganism is highly sensitive to ciprofloxacin and resistance to erythromycin.