Winning the War against Multi-Drug Resistant Diarrhoeagenic Bacteria

Drug-resistant-diarrhoeagenic bacteria are currently emerging healthcare challenge. This study investigated the effects of , , tetracycline and metronidazole combinations on such bacteria. Agar well diffusion method was employed to determine the inhibitory effects of the herbal extracts on diarrhoeagenic bacteria while Time-Kill Assay was used to determine bactericidal effects of the extracts against test isolates. Interactions between plant extracts and antibiotics were investigated using Checkerboard assay. Minimum inhibitory concentrations of the extracts against the bacterial isolates ranged between 3.125-50 mg/mL, while those of tetracycline and metronidazole ranged from 30-50 μg/mL. Synergism was observed against and for metronidazole + aqueous at all ratios. Generally, the combinations aqueous + ethanolic and aqueous + ethanolic showed more pronounced synergism against the than isolates with the fractional inhibition concentration (FIC) indices ranging from 0.32-0.95. Synergism of tetracycline + crude extracts and metronidazole combinations were more pronounced on the test isolates and especially on the Gram-negative organisms with FIC indices ranging from 0.41-0.91. Conclusion: The herbal extracts combinations and extracts-antibiotics combinations are synergistic on diarrhoeagenic bacteria at defined combination ratios.