Introduction: Many medicinal plants produce antioxidants and antimicrobial properties which protect the host from cellular oxidation reactions and other pathogens highlighting the importance of search for natural antimicrobial drugs.
Method : The antibacterial activity of 25, 50 and 100 mg/ml aqueous extract of garlic and onion on S.aureus, S. Typhi,P. aeruginosa and E. coli isolates were carried out using agar well diffusion method. The antibacterial activity of the aqueous plant extract were measured by zones of inhibition and the antibiotic sensitivity test of the bacteria isolates was done using the disc diffusion method.
Results: Inhibition zone diameter of 18 mm, 19 mm, 21 mm and 27 mm were observed for E.coli, P.aeruginosa, S.aureus, and S.Typhi respectively using 100 mg/ml of garlic while for onion, 11.5 mm, 12 mm, 12 mm and 13 mm inhibition zone diameter were observed for the same bacteria isolates respectively. It was observed that the increase in concentration of garlic is needed for better antibacterial activity while increasing concentration does not have a significant effect on the antibacterial activity of onion. The results of the antibiotic tests showed that most of the tested organisms exhibited multiple drug resistance to the conventional antibiotics including cotrimoxazole, chloramphenicol, amoxillin, streptomycin and septrin.
Conclusion: Garlic extract showed greater antimicrobial potential compared with onion extract and the widely used antibiotics. Thus, aqueous garlic extract may be more effective in the treatment of bacterial infections in order to overcomethe problem of multidrug resistance of bacterial pathogens.