variants
or less commonly C-diff
plural C. diff also C-diff
: a rod-shaped, spore-producing, gram-positive bacterial clostridium (Clostridium difficile) that occurs widely in soil and water and sometimes in human and animal intestines and that may produce a toxin causing intestinal illness (such as diarrhea) especially in those receiving antibiotic therapy
Many healthy people harbor a few C. diff among the millions of bacteria in the colon. When C. diff hangs out in the form of inert spores, it's harmless. But if antibiotic therapy knocks off the normal bacteria, C. diff springs to life, producing two toxins that attack the colon.—
Harvey B. Simon
Harvey B. SimonCite this Entry
“C. diff.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/C.%20diff. Accessed 5 Jul. 2026.
Copy CitationMedical Definition
C. diff
noun
variants
also C-diff
plural C. diff also C-diff
: a rod-shaped, spore-producing, gram-positive bacterium (Clostridioides difficile synonym Clostridium difficile) that occurs widely in soil and water and sometimes in human and animal intestines and that may produce a toxin causing intestinal illness (such as diarrhea) especially in those receiving antibiotic therapy
Many healthy people harbor a few C. diff among the millions of bacteria in the colon.—Harvey B. Simon
Harvey B. SimonAnyone admitted to the hospital with diarrhea and a recent history of using antibiotics or other drugs linked to C. diff infections is isolated immediately and tested for the bacteria.—Peter Eisler
Peter EislerC-diff, as it's called, is a rising problem across North America and in parts of Europe.—Ben Harder
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