Author(s): Sarita Das, Janaki Kumari Padhy and Pritilata Panda

Abstract: Anti-bacterial activity of methanolic extract of Tridax procumbens L. leaf (MTP) was evaluated against the common skin infection causing bacteria (Staphylococcus aureus and Pseudomonas aeruginosa) using various methods such as agar well method, modified agar well, disc diffusion method etc. and also the phytochemicals present in MTP were investigated. P. aeruginosa used in our study was a multidrug resistant strain. Phytochemical analysis of MTP revealed the presence of tannins, flavonoids and phenols. In agar well diffusion method at 25 mg/well concentration, P. aeruginosa showed a zone of inhibition (ZOI) of 3.3 cm, whereas S. aureus exhibited 1.7 cm of ZOI at same concentration of MTP. In modified agar well method, ZOI of P. aeruginosa and S. aureus were found to be 3.4 cm and 2 cm, respectively. In disc diffusion method S. aureus showed 0.8 cm of ZOI at 4 mg/disc concentration. P. aeruginosa had maximum ZOI i.e, 2.4 cm at 4 mg/disc and 2.1 cm at 3.2 mg/disc concentration. The colony forming units per ml (cfu/ml) were found to be reduced in a dose dependent manner in the MTP treated bacteria in comparison to control/wild bacteria, as evident from the results of both spread plate and absorbance method. MTP had more bactericidal activity against P. aeruginosa, in comparison to S. aureus in agar well, modified agar well and disc diffusion method.