COLONIZATION OF CONGENITALLY IMMUNODEFICIENT MICE WITH PROBIOTIC BACTERIA

We assessed the capacity of four probiotic bacteria (Lactobacillus aci dophilus, Lactobacillus reuteri, Lactobacillus casei GG, and Bifidobac terium animalis) to colonize, infect, stimulate immune responses in, a nd affect the grow th and survival of congenitally immunodeficient gno tobiotic beige-athymic (bg/bg-nu/nu) and beige-euthymic (bg/bg-nu/+) m ice, The bacteria colonized and persisted, in pure culture, in the ali mentary tracts of both mouse strains for the entire study period (12 w eeks), Although all adult and neonatal beige-euthymic mice survived pr obiotic colonization, some infant mortality occurred in beige-athymic pups born to mothers colonized with pure cultures of L., reuteri or L. casei GG, The probiotic bacteria manifested different capacities to a dhere to epithelial surfaces, disseminate to internal organs, affect t he body weight of adult mice and the growth of neonatal mice, and stim ulate immune responses, Although the probiotic species were innocuous for adults, these results suggest that caution and further studies to assess the safety of probiotic bacteria for immunodeficient hosts, esp ecially neonates, are required.