GI II

Question 1

C. difficile is a (G+ve/G-ve), shape, (aerobic/anaerobic), (spore-forming/non spore-forming)

Answer 1

C. difficile is a G+ve, bacillus, (anaerobic), spore-forming

Question 2

describe the pathophysiology of C. diff infection

Answer 2

Question 3

describe toxin A produced by C. diff

Answer 3

• toxin A
  
  • enterotoxin that alters the permeability of the cell membrane and leads to changes that cause outflux of water/electrolytes from cell → mild, watery form of diarrhea

Question 4

describe toxin B produced by C. diff

Answer 4

• toxin B = potent cytotoxin
  
  • inactivates small GTP-binding proteins → actin condensation and cell rounding → cell death (similar to diphtheria toxin)

Question 5

why is a C. diff culture not sufficient for diagnosis?

Answer 5

not all C. diff strains produce toxin

Question 6

describe the 2 reference tests used for C. diff diagnosis

Answer 6

Question 7

describe peritonitis and the most common cause of primary and secondary perotinitis

Answer 7

• primary peritonitis (spontaneous bacterial peritonitis)
  
  • occurs in up to 10% of patients with alcoholic cirrhosis
  • most common cause = E. coli
• secondary peritonitis
  
  • spillage of bacteria from the GI tract into peritoneal cavity

Question 8

Bacteroides fragilis is (G+ve/G-ve) and (aerobic/anaerobic)

Answer 8

Bacteroides fragilis is (G+ve/G-ve) and (aerobic/anaerobic)

Question 9

describe the 2 types of B. fragilis

Answer 9

Question 10

describe Whipple’s disease

Answer 10

Question 11

describe the clinical presentation of Whipple’s disease

Answer 11

• wasting illness; arthralgias, arthritis, fever, diarrhea
• small intestine, steatorrhea
• any physical findings of malabsorption
• neurological symptoms

Question 12

describe the diagnosis of Whipple’s disease

Answer 12

• biopsy: SI, endocardial, brain, synovial
  
  • PAS positive macrophages
• PCR: T. whipplei DNA