Antibacterial activity of medicinal herb and spice extracts

Purpose: This study aimed to test a variety of naturally occurring, medicinal and potentially food-compatible herb and spice extracts for their antimicrobial potential against a group of food borne bacterial pathogens. Design/methodology/approach: A total of 5 herbs and spices (garlic, thyme, cinnamon, marjoram and clove) collected from different markets in Alexandria were tested using the broth dilution method for determination of minimum inhibitory concentration (MIC), disc diffusion method and synergy assay using the checkerboard method on four types of food borne bacterial isolates obtained from food samples referred to the Central Lab of the High Institute of Public Health (HIPH). Findings: All the selected aqueous plant extracts exhibited antibacterial activities against all tested organisms with varying degrees. Garlic extract showed the maximum activity with MIC values ranging from 18.75 to 37.5 mg/ml. Garlic extract also caused inhibition of all tested bacterial isolates using the disc diffusion method. Staphylococcus aureus and Shigella were the most susceptible to crude aqueous extracts. Originality/value: The use of herbs and spices can provide an adequate degree of protection against food borne pathogens in processed foods. 1