Voluntarily exposure to a single, high dose of probiotic Escherichia coli results in prolonged colonisation

The ability of probiotic Escherichia coli to colonise the human gut was determined in a volunteer study following national (German) regulations. Five persons voluntarily took a single, high dose of Symbioflor®2, which contains 6 different probiotic E. coli genotypes, to assess tolerance of the product, after which presence of E. coli in their faeces was tested for a follow-up period of 30 weeks. Intake of the product did not result in severe side effect in any of the individuals, though mild side effects were observed. Stool analysis showed that the probiotic E. coli had colonised all five persons for a period of 10 to 30 weeks (mean: 18.7 weeks, median: 25.7 weeks). In two individuals there was evidence of competition between host E. coli and probiotic E. coli, while in two others total E. coli levels increased persistently with at least a factor of 10 as a result of the received dose. In one individual, who had lacked detectable levels of faecal E. coli at the start of the post-authorisation safety stud...