Antimicrobial activities of Hibiscus sabdariffa and Aspilia africana against clinical isolates of Salmonella typhi

Background: Plants hold prospects for novel drugs discovery against Salmonella typhi and its swift antibiotics resistance. This study aimed to determine the antimicrobial activities of Hibiscus sabdariffa and Aspilia africana extracts against clinical isolates of S. typhi. Methods: Active ingredients of plants were extracted using ethanol and constituted into Extracts I, II and III. Extract I is A. africana, Extract II is H. sabdariffa and Extract III is a combination of extracts of A. africana and H. sabdariffa. Phytochemical screening, antimicrobial sensitivity test (Agar Well Diffusion), Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) tests were conducted during this study. Results: Results on phytochemicals of H. sabdariffa and A. africana extracts showed phenols, saponins, tannins, reducing sugars, triterpenoids, coumarins, alkaloids and steroids. Antimicrobial sensitivity test showed that S. typhi was sensitive to all extracts indicating zones of inhibition of 29.0, 19.0 and 18.5 mm for Extract I, II and III respectively while resistant to lower concentrations of Extract I at 100, 50 and 25 mg/ml. Resistant S. typhi was sensitive to Extract I, II, and III (21.0, 19.0 and 19.0 mm) respectively at 200 mg/ml while resistant to both Extract I and II at (100, 50 and 25 mg/ml) and (50 and 25 mg/ml) respectively. MIC experiments showed 3.125, 6.25 and 3.125 mg/ml against sensitive S. typhi and 25, 12.5 and 12.5 mg/ml against resistant S. typhi for Extract I, II and III respectively. MBC values were 25, 12.5 and 12.5 mg/ml against sensitive S. typhi and 50, 25 and 25 mg/ml against resistant S. typhi for Extract I, II and III respectively. Plant extracts, when combined with ciprofloxacin (concentration), indicated MBCs of 0.19, 0.19, and 0.39 mg/ml against sensitive S. typhi compared with 0.19, 0.097 and 0.19 mg/ml against resistant S. typhi for Extract I, II and III respectively. Conclusion: These plant extracts showed great antimicrobial activities and therefore could be exploited and harnessed for future antibiotic drug discovery.