This research has studied the antibacterial effect of aqueous garlic (Allium sativum )  Linn extract on certain pathogenic Gram positive (Staphylococcus aureus, Staphylococcus saprophyticus, Streptococcus pneumonia and Streptococcus faecalis) and Gram negative bacteria (Escherichia coli, Enterobacter cloacae, Klebsiella pneumonia, Proteus mirabilis, Pseudomonas aeruginosa and Acinetobacter haemolyticus) and determined the optimal conditions for extraction of these materials. The results have revealed that, a concentration of 750 to 1000 µg/ml of the aqueous garlic extract has high antibacterial effect, which reached to 100% with some exceptions. The 6 hrs after extraction and 30-50°C were found to be the optimal circumstances to reach the optimal efficacy for inhibiting the growth of pathogenic bacteria. Whereas, the temperature of 70-100°C led to loss of the efficacy of aqueous garlic extract.  

In general, there is high efficacy for aqueous garlic extract against certain pathogenic bacteria and the response was varied with the different bacteria, concentration of the extract, extraction period and temperature.