Interaction of Ciprofloxacin and Extract of Hibiscus sabdariffa Linn (Roselle) Calyses in Antimicrobial Assays by ‘Agar-well Cross-reaction Technique’

Abstract

Aims: To evaluate the antibacterial activities of aqueous extract of Hibiscus sabdariffa Linn calyces and ciprofloxacin, separately and in combination, and introduce a simple method in the study of drug interactions. Study Design: Experimental design. Place and Duration of Study: Department of Biological Sciences, Ondo State University of Science and Technology, Okitipupa, between March 2013 and June 2015. Methodology: Antimicrobial assays using five bacterial isolates including S. aureus, Pseudomonas aeruginosa, and S. aureus NCTC 6571, by agar-well diffusion method were performed. Interaction assay of extract and ciprofloxacin by an ‘Agar-well Cross-reaction Technique’ was performed. Inferences for synergistic, additive, indifferent or antagonistic interaction were drawn from the percentage differences in the inhibition zone diameters (IZDs) produced. Results: All test bacteria were susceptible to the extract, IZDs ranging from 10 mm to 32 mm. Four test bacteria were susceptible to ciprofloxacin, IZDs ranging from 15 mm to 35 mm. Out of the twenty five interactions against S. aureus O1, there were 6 (24%) synergistic, 6 (24%) additive, 3 (12%)  indifferent, 5 (20%) antagonistic reactions, and 5 (20%) showed no activity. Out of the twenty five interactions against P. aeruginosa PA2, there were 2 (8.0%) synergistic, 2 (8.0%) additive, 1 (4%) indifferent, 9 (36%) antagonistic reactions, and 11 (44%) showed no activity. Summing up the fifty interactions for the two test isolates, 36 (72%) interactions were favorable or indifferent while 14 (28%) interactions were antagonistic. Results of Chi square test showed this to be statistically significant (P = .05). Conclusion: H. sabdariffa calyces extract posseses antibacterial properties similar to ciprofloxacin, and inhibited ciprofloxacin-resistant isolates. Concomitant use of ciprofloxacin and H. sabdariffa extract may not produce antagonistic reactions. The ‘Agar-well Cross-reaction Technique’ proved to be sensitive and effective, eliminating many of the difficulties experienced with other methods of studying drug interactions.