CPA1 and infection: Therefore, no impact of non-pathogenic CpA and E. coli strains on the course of infection with C. suis could be deduced from the results of the trial—neither for improvement nor for aggravation of the clinical outcome of cystoisosporosis, and the underlying hypothesis of a beneficial effect of an early competitive colonization with probiotic bacterial strains prior to contact with pathogens had to be rejected for this model.