Research is increasingly showing that a diverse and healthy gut microbiome plays a role in fine-tuning the immune system.  In fact, gut-associated lymphoid tissue (GALT) represents almost 70% of the entire immune system. Probiotics play a role in defining and maintaining the delicate balance between necessary and excessive defense mechanisms including innate and adaptive immune responses. Advances, such as the success of fecal transplantation for antibiotic-associated diarrhea caused by C. difficile, illustrate the example that microbiota are to be considered an optimal therapy for infectious disease ^[1].  One of the ways probiotics promote human health is by inhibiting the growth of pathogenic microbe and consequently reduce recurrent infections. The gut microbiota largely regulate the homeostasis as well as the development of immune cells. Probiotics confer protection against pathogen colonization by inducing their direct killing, competing with nutrients, and enhancing the response of the gut-associated immune repertoire, therefore suppress the growth of potential pathogenic microbe and maintain the immune balance ^[2].