Authors : S.S. Taiwo , B.A. Oyekanmi , Y.O. Adesiji , O.O. Opaleye and O.A. Adeyeba
Abstract: The aim of this study is to investigate the antibacterial effects of two plant extracts, Citrus aurantifolia linn (lime) and Tithonia diversifolia poaceae (sunflower) commonly used as traditional medicines in Nigeria. The antibacterial activities of aqueous extracts of these two plants were evaluated using disk diffusion susceptibility testing on 53 fresh human bacterial pathogens isolated in Ladoke Akintola University Teaching Hospital, Osogbo, Nigeria. These isolates included 27 Staphylococcus sp., 15 Escherichia coli, 3 Klebsiella sp., 4 Proteus sp. and 4 Pseudomonas sp. The Mean Zone Diameter (MZD) of inhibitions to 5 �L of Citrus aurantifolia linn extracts are 10, 12, 11, 17 and 16 mm for Staphylococcus sp., E. coli, Klebsiella sp., Proteus sp. and Pseudomonas sp., respectively. The MZD of inhibitions to 5 �L of Tithonia diversifolia poaceae extract are 1, 1, 0, 8 and 0 mm and for 5 �g ciprofloxacin (control) disk are 29, 19, 20, 25 and 15 mm for these respective organisms. Forty four percent (12 of 27) of the Gram positive and 69% (18 of 26) of the Gram negative pathogens showed Zone Diameter (ZD) of inhibition = 10 mm to 5 �L extract of Citrus aurantifolia linn. Four percent (1 of 27) of the Gram positive and 8% (2 of 26) of the Gram negative pathogens showed ZD of inhibition = 10 mm to 5 �L of Tithonia diversifolia poaceae. In comparison, 93% of the Gram positive (25 of 27) and 65% (17 of 26) of Gram negative pathogens showed zone diameter of inhibition = 10 mm to 5 �g ciprofloxacin (control disk). When compared to ciprofloxacin, 5 �L extract of Citrus aurantifolia linn possess approximately 33% antistaphylococcal activities of 5 �g ciprofloxacin and approximately the same activity on the Gram negative bacterial isolates tested (p = 0.2767). However, 5 �L extract of Tithonia diversifolia poaceae does not possess any appreciable antibacterial effect on any of the isolates when compared to 5�g ciprofloxacin disc (p = 0.0045) or when compared to 5 �L extract of Citrus aurantifolia linn (p = 0.0149). Citrus aurantifolia linn showed promising broad spectrum antibacterial effects on human pathogens.
S.S. Taiwo , B.A. Oyekanmi , Y.O. Adesiji , O.O. Opaleye and O.A. Adeyeba , 2007. In vitro Antimicrobial Activity of Crude Extracts of Citrus aurantifolia Linn and Tithonia diversifolia Poaceae on Clinical Bacterial Isolates. International Journal of Tropical Medicine, 2: 113-117.