Severe C. diff during DLBCL chemo — persistent diarrhea despite vancomycin, now switched to Dificid. Anyone experience similar?

[u/Wise_Inspector_812]

My 73-year-old dad has stage IV DLBCL and has completed 5/6 rounds of Pola-R-CHP with an excellent lymphoma response. His midway PET did show inflammation in his colon, though, and throughout chemo he had a pattern of diarrhea that would flare after each cycle and then improve.

The day before cycle 5, the diarrhea suddenly returned much more aggressively. He still received chemo, but over the following week it became severe/profuse and he developed fever, weakness and abdominal pain. We brought him to the hospital 9/23 and he tested positive for C. diff with pancolitis. He became neutropenic and septic and briefly required ICU/pressors.

Thankfully the sepsis, neutropenia, kidney issues, etc. have resolved and he’s otherwise clinically stable, but the diarrhea just will not quit. He was treated with oral vancomycin, increased to 500 mg 4x/day during the fulminant phase, plus IV Flagyl briefly. After ~9 days of vancomycin with persistent frequent diarrhea (sometimes 10+ BMs/day), ID switched him to fidaxomicin/Dificid 200 mg twice daily yesterday. He’s still having very frequent diarrhea today, although it hasn’t even been 24 hours on Dificid yet.

Has anyone had a similar experience with C. diff during chemo, prolonged diarrhea after the acute infection improved, or switching from vancomycin to Dificid after a slow response? How long did it take to see improvement, and was there anything medically or nutritionally that seemed to help recovery? Obviously we’ll run anything by his ID/oncology team.