Can bacterial infection cause gastrointestinal fistula?

Yes: For instance an infection in the wall of the colon triggered by diverticulitis can eat through the colon lining and cause a channel to form between the colon and a nearby structure like the bladder. This channel is called a fistula. In this example one symptom might be passing gas out your bladder (pneumoturia).

Yes: Bacteria can cause a fistula. Bacteria are felt to play a role in crohn's disease, which can result in fistula. Also, complications of infections such as diverticulitis can result in abscess and fistula formation.