Antibacterial Activity of Crude Aqueous Extracts of Tithonia diversifolia from Chichiri Area in Blantyre District, Malawi

Abstract

The global challenge of antimicrobial resistance has spurred scientific research efforts to find alternative sources of new antibiotics. The ethnopharmacological importance of Tithonia diversifolia is well-known. The present study's aim was to evaluate the in vitro activity of crude aqueous leaf, stem and root extracts of locally growing Tithonia diversifolia against the clinical bacterial isolates: E. coli, K. pneumoniae, and P. mirabilis. To obtain antibacterial activity data, the Broth macrodilution testing and Zone of inhibition Kirby-Bauer approaches were used. Estimated diameters of zone of inhibition showed leaf extracts of Tithonia diversifolia had significantly greater antibacterial activity (19.5±3.9 mm, 95% CI: 15.4-23.6 mm) than stem (15.2±2.0 mm, 95% CI: 13.0-17.3 mm, p= 0.021) or root extracts (15.0±2.1 mm, 95% CI: 12.8-17.2 mm, p=0.019). K. pneumoniae was the most susceptible isolate to growth inhibition by extracts from all plant parts. In broth macrodilution testing, leaf extracts exhibited greater potency on all study isolates compared to stem and root extracts. These findings support the traditional use of Tithonia diversifolia decoctions and infusions in infectious processes that are due to these pathogens and further strengthens recommendations for additional work to isolate and characterize the bioactive chemical compounds responsible for the observed antibacterial properties of the plant.