A Comparison of the Antimicrobial Effectiveness of Aqueous Extracts of Garlic, Ginger and Lime and Two Conventional Antibiotics on Escherichia coli, Salmonella spp., Shigella spp. and Bacillus cereus.

The antimicrobial effectiveness of extracts of garlic, ginger and lime on Escherichia coli, Salmonella spp., Shigella spp. and Bacillus cereus were ascertained and compared with that of the conventional antibiotics of Amoxicillin and Ampicillin using the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). The plant extracts showed varied activity on the test organisms with garlic showing a stronger antimicrobial activity of 150mg/ml, 50mg/ml and 100mg/ml on Salmonella, Shigella and Bacillus respectively compared to MIC of 250mg/ml of lime extracts on both Salmonella and Shigella and 150mg/ml on Bacillus spp. whilst ginger was totally ineffective at the highest concentration of 500mg/ml on all test organisms. MBC’s of garlic extract on Shigella and Bacillus cereus was generally lower compared with Lime. The lowest and highest MBC’s was shown by garlic on Shigella (150mg/ml) and Salmonella (500mg/ml) respectively. Generally, the MIC’s and MBC’s of the conventional antibiotics were lower compared with the plant extracts. However, garlic exhibited similar antimicrobial activity as Amoxicillin on Shigella (MIC=50mg/ml) and Bacillus cereus (MIC=100mg/ml) with no difference in Least Significant Difference (M1-M3=78.6254). Garlic also retained the same MIC activity with Ampicillin on Shigella (50mg/ml). The MBC’s of garlic and Amoxicillin were the same (200mg/ml). This study confirms the antimicrobial potential of these plants extracts especially garlic on the test bacteria and suggests the possibility of employing them as household remedies to some bacterial infections.