Biofilms are nasty stuff. I did part of my master's thesis on them. They group together and communicate with each other (with electrical grids, according to Dr. Costerton, one of the forefront researchers of biofilms before he passed away). Some species use the film to coordinate a certain percentage of bugs stay in a "dormant" state, so they won't intake an antibiotic and die.

For artificial joints like a hip and a knee joint, you have a lot of exposed materials like titanium, stainless steel, or medical polymer, so it doesn't have an immune system. Getting a biofilm infection forming on an artificial joint sometimes means taking the implant out, even if it's working fine.

So biofilms are a tough problem. They're far more sinister than conventional bacterial colonies. Since this is in the digestive tract, I wonder if some type of detergent can be found that simply dissolves the film matrix, washing away the bacteria and fungi.