The Flip Side of Herbal Remedies

Aim: This study was carried out to determine the fate of bacteria exposed to sub lethal concentrations of bioactive extracts of some plants. Methods: Ethanolic extracts of Tetrapleura tetraptera (leaves), Prosopis africana (bark) and Buchholzia coriaceae (seeds) were assayed for phytochemical contents, antibacterial activities and induction of multidrug resistance in bacteria hitherto susceptible to test drugs using standard methods. Results: Results showed that the three plants contain alkaloids, glycosides, saponins, flavonoids and reducing sugars in addition to other metabolites. The extracts showed appreciable inhibitory effects on some species of Alcaligenes, Bacillus, Enterobacter, Escherichia, Klebsiella, Pseudomonas and Salmonella. The minimum inhibitory concentration (MIC) ranged (mg/ml) from 3.13 – 50.0 for P. africana; 3.13 – 6.25 for B. coriaceae to 1.25 – 50.0 for T. tetraptera. Exposure of drug susceptible bacterial species belonging to the genera Escherichia, Enterobacter, Klebsiella, Proteus, Pseudomonas and Salmonella to different concentrations of these extracts resulted in emergence of clones resistant to some commonly available antibacterial agents. Conclusion: Plant extracts are capable of dose-related inducement and sustenance of multiple antibiotic resistance among some bacteria. This study has shown that despite its positive contribution, herbal remedies incorporate the hitherto unexplained increase in emergence of multidrug resistance among (enteric) bacteria in our communities.