If I'm reading this right, the B2 strains of E. coli make up about 1/3 of the E. coli typically resident in the human gut. This group produces colibactin which can induce unwanted chromosomal instability.
In trying various probiotics, it does not seem to make sense to skip over Nissle 1917 due to it being in the B2 group if 1/3 of what we have is already of that group.
On the benefit side, high quality studies seem to show remission rates similar to mesalamine. As for safety, the strain is recommended as guideline therapy by the Deutsche Gesellschaft für Gastroenterologie.
In trying various probiotics, it does not seem to make sense to skip over Nissle 1917 due to it being in the B2 group if 1/3 of what we have is already of that group.
On the benefit side, high quality studies seem to show remission rates similar to mesalamine. As for safety, the strain is recommended as guideline therapy by the Deutsche Gesellschaft für Gastroenterologie.