The aim of the present study was to evaluate aqueous, ethanolic and ethyl acetate extracts of plant Calotropis gigantea traditionally used in Indian folklore medicine for the treatment of various bacterial and fungal infections were investigated for in vitro antibacterial activity against pathogens namely Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae by disc diffusion method compared with standard antibiotic antibacterial activity. The results revealed that, among the different types of tested extract, ethyl acetate extract of leaves showed 16.9±1.06mm, 19.4±0.54mm, and 21.5±0.85mm maximum zone of inhibition against E.coli, K. pneumoniae and S.aureus respectively. Minimum Inhibitory Concentration (MIC) was measured by broth dilution method. Results revealed that MIC value was recorded for aqueous extract at 2.75 mg/ml against S.aureus and K. pneumoniae respectively, whereas for ethyl acetate extract MIC was observed at 2.25mg/ml for E.coli and 2 mg/ml for both S.aureus and K. pneumoniae. In case of ethanol MIC value was recorded at 2.25mg/ml for S.aureus and 2.5 mg/ml for both E.coli and K. pneumoniae. The results provided justification for the use of plants in folk medicine to treat various infectious diseases.
