In vitro Antimicrobial Activity of Tithonia diversifolia Leaf Extracts on Bacterial Isolates from Wound Infections from a Nigerian Hospital

The in vitro antimicrobial activity of the Aqueous (A), Aqueous-Ethanol (AE), Aqueous-Ethanol-Ethylacetate (AEE), Ethanol (E) and Ethylacetate (EE) extracts of the Tithonia diversifolia leaf on bacterial isolates from wound infections was studied. These isolates include Staphylococcus aureus, non-coagulase Staphylococcus, Pseudomonas, Proteus and Klebsiella sp. The Mean Zone Diameter (MZD) of inhibition to 0.06 mL of each of the extract to Staphylococcus sp., 14, 14, 14, 14 and 15 mm, non-coagulase staphylococcus sp., 7, 6, 0, 3 and 4 mm, Pseudomonas sp. 10, 11, 11, 10 and 10 mm, Klebsiella sp. 10, 9, 10, 9 and 10 mm and Proteus sp. has no mean zone diameter. The MZD for 10 μg Streptomycin (control) disk shows 14, 14, 7, 7 and 7 mm for Staphylococcus sp., non-coagulase staphylococcus sp., Pseudomonas sp., Klebsiella sp., Proteus sp. About 82% Staphylococcus aureus have Zone Diameter (ZD) of inhibition above 10 mm to A extract, 82% to AE, 79% to AEE, 82% to E and 85% to EE extracts. Non-Staphylococcus aureus shows no zone diameter of inhibition above 10 mm, 40% Pseudomonas sp. shows zone diameter of inhibition above 10 mm to A, 44% to AE, 36% to AEE, 40% to E and 32% to EE extracts. About 15% Klebsiella sp. shows zone diameter of inhibition above 10 mm to A, 15% to AE, 25% to AEE, 4% to E, 4% to EE. In comparison, 82% of Staphylococcus aureus shows zone diameter of inhibition above 10 mm to 10 μg streptomycin (control) disk. 10% for Klebsiella sp., 85% for non-coagulase Staphylococcus aureus and none for Pseudomonas sp. and Proteus sp.When compared with the control drug, 0.06 mL of each of the leaf extract possesses the same antistaphylococcal activity but possesses twice the effect on gram negative bacteria isolated. However, 0.06 mL of each of the extracts has an appreciable antibacterial effect except for Proteus sp. compared to 10 μg streptomycin disk. Tithonia diversifolia leaf extract shows a promising broad spectrum antibacterial effect on human pathogens. The minimum inhibitory concentration of all the extracts to the organism except for Proteus sp. ranges from 125-250 μg mL-1 while the minimum bactericidal concentration ranges from 500-1000 μg mL-1. Tithonia diversifolia leaf showed promising broad spectrum antibacterial effect on human pathogens.