Clostridium difficile

Question 1

What type of bacteria is C. difficile?

Answer 1

Gram-positive bacillus (rod)

Question 2

Why is C. difficile hard to eradicate from the environment?

Answer 2

forms endospores - stability and persistence

Question 3

Describe 2 types of exotoxins produced by C. difficile.

Answer 3

Both are glucosyltransferases that glycosylate and inactivate Rho-family GTP-binding proteins:

1. Enterotoxin A - causes excessive fluid secretion (diarrhoea), inflammatory response and has some cytopathic effect
2. Cytotoxin B - disrupts protein synthesis, cytoskeleton disorganisation

Question 4

How is C. difficile transmitted?

Answer 4

contamination of environment with spores

Question 5

Is C. difficile part of the normal human flora?

Answer 5

Yes, minor component of large intestine flora

Question 6

When does C. difficile become pathogenic?

Answer 6

proliferates when predominant species in large intestine community are suppressed by (virtually all) antimicrobial drugs

Question 7

What type of disease does C. difficile cause?

Answer 7

varies from:

1. diarrhoea
2. pseudomembranous colitis - pseudomembranous exudate (composed of mucus, fibrin, inflammatory cells and cell debris overlying an ulcerated epithelium)

Question 8

How is C. difficile infection diagnosed?

Answer 8

1. cultured from stool sample and identified by routine anaerobic procedures (anaerobic on blood agar)
2. ELISA for exotoxins A and B (more rapid)
3. PCR

Question 9

Describe the supportive management of C. difficile infection.

Answer 9

1. Stop: antibiotics, proton pump inhibitors, immunosuppressant therapy/steroids, laxatives and prokinetics, opioids
2. Fluid replacement

Question 10

Describe the specific management of C. difficile infection.

Answer 10

Antibiotics:

• not severe (or enteral route not available) = METRONIDAZOLE
• severe = VANCOMYCIN (can only be given orally)

Question 11

What type of antibiotic is vancomycin and what is its MOA?

Answer 11

glycopeptide - binds cell wall amino acids, preventing peptidoglycan chain elongation

Question 12

Which clostridium species cause tetanus and botulism?

Answer 12

C. tetani

C. botulinum

Question 13

Name an antibiotic type that particularly increases risk of C. difficile infection.

Answer 13

cephalosporins