Inhibitory effects of spices and herbs towards Shigella sonnei and S. flexneri

The use of spices and herbs, their essential oils or their active compounds as means of control of pathogens constitutes an alternative to chemical additives In the present study the antibacterial activities of cloves, thyme, oregano, rosemary and basil on Shigella have been established. Although in a model system in agar media addition of 1% basil could contribute to the 'hurdle' principle and delay outgrowth of Shigella sp. this was not confirmed in real food conditions: the presence of 1% basil did not affect growth of Shigella in potato puree at 22 degrees C or survival at 7 degrees C in spaghetti sauce. Thyme and essential oils and thymol and carvacrol showed inhibition of Shigella sp. in the agar well diffusion method (MIC 0.1-1.0%) and they have potential to be used as a desinfectant in the washing water e.g. in the process line of minimal processed vegetables. However, more studies combining sensoric properties with microbial analysis are needed to investigated the possible use of these compounds.