Clostridium difficile infection is caused by antibiotics which kill off the ordinary good bacteria allowing the C. diff to flourish in the gut.
C. diff causes inflammation of the large intestine and CDAD (C. diff associated diarrhea); CDAD is caused by toxins that cause bloating, diarrhea and abdominal pain.
That doesn't sound so terrible, rather like the flu, except C. diff is really hard to get rid of. An infection can go on for months or years, preventing people from leaving the house. And as the ability to absorb nutirion is impeded. they can waste away and die.
So when I was in the ICU on two types of IV antibiotics and overheard the doctor ask my nurse if I had diarrhea, I knew why he was asking and was not a happy camper.
Image credit: Clostridium difficile 01 by CDC/Lois S. Wiggs [public domain], via Wikimedia Commons.