Siri Roßberg, Theresa Keller, Katja Icke, Valentina Siedmann, Imke Lau, Thomas Keil, Susanne Lau

• Background The allergy preventive effects of gut immune modulation by bacterial compounds are still not fully understood. Objective We sought to evaluate the effect of bacterial lysate applied orally from the second until seventh months of life on the prevalence of allergic diseases at school age. Methods In a randomized, placebo‐controlled trial, 606 newborns with at least one allergic parent received orally a bacterial lysate consisting of heat‐killed Gram‐negative Escherichia coli Symbio and Gram‐positive Enterococcus faecalisBackground The allergy preventive effects of gut immune modulation by bacterial compounds are still not fully understood. Objective We sought to evaluate the effect of bacterial lysate applied orally from the second until seventh months of life on the prevalence of allergic diseases at school age. Methods In a randomized, placebo‐controlled trial, 606 newborns with at least one allergic parent received orally a bacterial lysate consisting of heat‐killed Gram‐negative Escherichia coli Symbio and Gram‐positive Enterococcus faecalis Symbio or placebo from week 5 until the end of month 7. A total of 402 children were followed until school age (6‐11 years) for the assessment of current atopic dermatitis (AD), allergic rhinitis (AR), asthma and sensitization against aeroallergens. Results AD was diagnosed in 11.0% (22/200) of children in the active and in 10.4% (21/202) of children in the placebo group. AR was diagnosed in 35% (70/200) of children in the active and in 38.1% (77/202) children in the placebo group. Asthma was diagnosed in 9% (18/199) of children in the active and in 6.6% (13/197) of children in the placebo group. Sensitization occurred in 46.5% (66/142) of participants in the active and 51.7% (76/147) in the placebo group. Conclusion An oral bacterial lysate of heat‐killed Gram‐negative Escherichia coli and Gram‐positive Enterococcus faecalis applied during the first 7 months of life did not influence the development of AD, asthma and AR at school age.…