The effect of seasonal variation on the antibacterial activity of Tithonia diversifolia (Hemsl.) A. Gray leaf extracts against pathogenic bacterial strains

The study investigates the antibacterial activity of Tithonia diversifolia leaves, including methanol, ethanol and water extracts, against Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Proteus vulgaris, Micrococcus luteus, Staphylococcus aureus, Bacillus subtilis, Clostridium sporogenes using the agar well diffusion technique . Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were performed on bacteria by a modification of the standard agar dilution method. Qualitative phytochemical analysis of leaf extract was determined by standard analytic methods. The study found that Klebsiella pneumoniae and Bacillus subtilis showed less susceptibility to water extracts, while Pseudomonas aeruginosa and Proteus vulgaris were sensitive to all water extract samples with zone of inhibition of 20.5 mm and 20.0 mm, respectively. However, all methanol extracts were susceptible to Pseudomonas aeruginosa, Proteus vulgaris , and Staphylococcus aureus with zones of inhibition of 18.0, 14.0, and 15.0 mm, respectively. Serratia marcescens showed less susceptibility to most methanol extracts, while Clostridium sporogenes showed susceptibility to all ethanol extracts. MICs and MBC values against bacterial strains ranged from 12 - 50 mgmL ^-1 and 25 - 100 mgmL ^-1 respectively. The study concluded that the leaves of Tithonia diversifolia contain phytochemicals with broad-spectrum antimicrobial effects, with ethanol extracts showing high sensitivity. The concentration of these phytochemicals varies by season, with higher levels observed during rainy seasons. The study highlights the potential of Tithonia diversifolia leaves for antimicrobial properties.