He's speaking about clostridium difficile colitis, aka c. Difficile.
They are intestine bacteria that assist in digestion, but it is considered a "bad" bacteria. Normally when you're in good health, your body is able to keep the count down on this. The growth is typically caused by another illness, and taking antibiotics. You can take antibiotics to kill these bacteria, but it also targets and kills your "good" bacteria. If your c-diff doesn't stay under control, you can develop clostridium difficile colitis.
Clostridium difficile colitis is caused by a large population of c. Difficile bacteria inside your intestine in colon. These cells produce 2 toxins, which both attack your intestine wall. Without proper care, you can develop ulcers. Also, in rare cases, it can be deadly.
Symptoms are diarrhea, cramps, and when it is advanced fever and weakness.
If you do have this issue, see a doctor. He can prescribe you with antibiotics that should do the job. If not, theres also flagyl.
Im no md, and i'm just a highschool student. I don't guarantee any of what I just said as being correct, its just what i've picked up.