Abstract: The antimicrobial activity of methanol, aqueous and petroleum ether extracts of leaves of
Calotropis procera against six foodborne pathogenic bacteria, namely Escherichia coli ATCC 43889, Escherichia
coli ATCC 35150, Escherichia coli ATCC 43890, Bacillus cereus ATCC 14579, Bacillus cereus ATCC 10987 and
Bacillus cereus ATCC 10876 was determined using paper disk methods. The growth of six bacterial isolates
inhibited by the leaf extract with methanol and water where petroleum did not show any effect. Methanol extract
gave the highest zone of inhibition (2.4 cm) against Bacillus cereus ATCC 10987 followed by water extract (1.70
cm) against E. coli ATCC 43889; whereas, petroleum ether extracts did not show any antibacterial activity. The
minimum inhibitory concentration and minimum bactericidal concentration were ranged from 33.75-67.5 μg/ml.
Cell viability assay showed the complete inhibition of all the tested microorganism within 200 min. This study
revealed that the C. procera leaf extract demonstrated strong inhibitory effect on the test organisms that could
be a good support for the use of C. procera in traditional medicine.