Antibacterial activities of some plants used as condiments and spices in Nigeria

The aim of this experiment was to determine the antibacterial actions of the extracts of garlic, ginger, onion, basil, sweet and hot peppers on some human pathogenic bacteria (Klebsiella pneumoniae, Streptococcus faecalis, Corynebacterium diphtheriae, Pseudomonas aeruginosa and Escherichia coli). Crude and filtered extracts of the plants were prepared by using water and tested on the pathogenic bacteria by agar diffusion method. All the spices and condiments showed varying antibacterial effects. Garlic was most effective; its extracts inhibited the growth of all the tested microbes with zones of inhibition ranging from 2 to 10 mm. Onion’s extracts killed Kl. pneumoniae, Strep. faecalis and E. coli. The onion’s crude extract bacteriostatically prevented Coryne. diphtheriae and Ps. aeruginosa from growing. It was observed that all the tested organisms except Kl. pneumoniae and Strep. faecalis did not grow in the presence of ginger. Also, filtered extract of the ginger did not inhibit the growth of the E. coli. Basil did not stop the growth of the organisms except Strep. faecalis. Extracts of sweet and hot peppers appeared inhibitory although crude extract of the former plant did not prevent the growth of Kl. pneumoniae. Boiled sweet pepper extract did not stop Coryne. diphtheriae from growing. Filtered extract of hot pepper killed Coryne. diphtheriae but did not show any zone of inhibition on other microorganisms.