Antibacterial activities of aqueous and methanol extracts of Nigella sativa on some multiple drug resistant diarrheic bacterial agents

Combinations of various antimicrobial agents have been introduced as an extra successful strategy to combat multiple drug resistant infections. This study was undertaken to evaluate the effects of Nigella sativa seeds on several multi-drug resistant diarrheic bacterial agents. 30 Stool samples were collected from Lagos State University Teaching Hospital (LASUTH), in Nigeria and standard biochemical tests were performed to confirm the diarrheic isolates. Then, antimicrobial susceptibility testing was done on the organisms, followed by screening the effectiveness of Nigella sativa seed extracts on the bacterial agents obtained from the samples. 16 samples tested positive for diarrheic agents Escherichia coli, Escherichia coli 0157H:7 and Klebsiella pneumoniae. The methanolic extracts of Nigella sativa showed the highest zone of inhibition of 12mm for K. pneumoniae at a concentration of 300mg/dl ,10mm for E. coli 0157H:7 at a concentration of 200mg/dl, and 10mm for E. coli at a concentration of 200mg/dl, respectively. The methanolic extracts showed much stronger activity than the aqueous extracts of Nigella sativa which did not show significant activity towards the diarrheic agents isolated.