Abstract

Objective: To report the antimicrobial effect and biofilm forming capacity of the uropathogenic strains that have been isolated from recurrent urinary tract infections (UTIs) in the presence of Hibiscus sabdariffa (H. sabdariffa) extract. Methods: Six Escherichia coli and two Klebsiella pneumoniae isolates were collected from patients with recurrent UTIs. The susceptibility of bacterial isolates to H. sabdariffa extracts were tested by determining their minimum inhibitory concentrations (MICs), and minimum bactericidal concentration (MBC) by using the broth microdilution method in accordance to Clinical and Laboratory Standards Institute guidelines. Time-kill curves were plotted against the eight isolates based on the MIC results. The biofilm forming capacity of the isolates were evaluated using the microtiter plate assay. Detection of biofilms was done using the crystal violet staining method. Results: Various levels of the extracts MIC were observed against all the uropathogenic isolates. MIC values ranged from 0.5 to 4 mg/mL, and MBC values ranged from 8 to 64 mg/mL. Both the time-kill experiment and MBC-MIC ratio demonstrated that the extracts' effect was in general, bacteriostatic. The biofilm capacity inhibition assay results showed that extracts inhibited biofilm production of all the isolates. The level of biofilm inhibition however, had varied among the bacterial strains and ranged from 8%-60% reduction in optical density. Conclusions: The results of the study support the effective potential of H. sabdariffa extract to prevent recurrent UTIs and to emphasize the significance of the plant extract, in order to approach it as a potential antimicrobial agent.

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