MBIO 4823 Exam 5 A
Fully Certified Latest Updated Exam
Study Guide 2025/2026.
What is C. diff known as and what is its full name? - ansClostridioides (Clostridium)
difficile. A new SUPERBUG of our times
What are two diseases associated with C. diff? - ansClosridium difficile- Associated Disease
(CDAD) and Pseudomembranous Colitis
Who reclassified C. diff? - ansPaul Lawson, Diane Citron, Kerin Tyrell, Sydney Finegold
What part of the GI tract does C. diff affect? - ansMainly found in Jejunum, where continued
digestion and absorption of monosaccharides, amino acids, fatty acid, water pH 4-5.
What is the gram reaction of all clostridial species? - ansAll clostridial species are Gram
positive
What kind of organism is C. diff? - ans*Obligate Anaerobe*
How many toxins does C. diff produce? - ansProduces *2 toxins*:
-*A-enterotoxin*
-*B-A-B cytotoxin*
Does C. diff form spores? - ans*Spore-former*
What is C. diff recognized as now? - ans-Now recognized as a *SUPERBUG*
-Many strains are susceptible to antibiotics but quickly becoming a major problem in
hospitals
When C. diff was recognized as a pathogen in 1960, what was it treated as? - ans-First
recognized as a pathogen when isolated from wounds, abscess, blood, and pleural fluid of
patients with a variety of illness- *but still not a problem*
What was C. diff discovered to cause in 1978? - ans-Discovered to *cause
pseudomembranous colitis (PMC).* The first association between C. diff and PMC
What else was discovered about patient symptoms in the year 1978? - ansThe same year *C.
difficile* was isolated from patients with the illness or experiencing postoperative *diarrhea*
What was discovered after antibiotics were used to treat C. diff? - ans*But it was not
anticipated that antibiotics used successfully to treat one bacterial infection could cause
another infection in the same patient! First instance of this.*
What is first step of the *disease process* with C. diff? - ans1. *C. difficile* vegetative cells
and spores are ingested:
-*vegetative cells are killed by stomach acid but spores survive*
What is the second step in C.diff disease that occurs upon exposure to bile acids? - ans2.
*Spores germinate in the small bowel* upon exposure to bile acids
How does the flagella support C. diff disease progression/movement to colon? - ans3.
*Movement to colon by flagella and polysaccharide capsule protects against phagocytosis*
What is the fourth step in C. diff disease progression? - ans4. Organisms *multiply in colon*
and adhere to epithelial cells
Describe the symptoms as C. diff cells *multiply in colon.* - ans-Local production of A & B
toxins
-Production of alpha-TNF, inflammation, increased vascular permeability, neutrophile and
monocyte recruitment
What is the fifth step of C. diff progression? - ans5. Opening of epithelial cell junctions and
cell apoptosis
After the sixth step involving hydrolytic enzymes, what occurs in C. diff progression? - ans6.
Local production of hydrolytic enzymes: *connective tissue degradation*
