GRAM POSITIVE RODS. PART 3B

Question 1

What are the recognized types of Clostridium perfringens based on surface antigens and major toxins produced?

Answer 1

There are five recognized types: A, B, C, D, and E.

Question 2

Which types of C. perfringens cause disease in humans?

Answer 2

Types A and C cause disease in humans.

Question 3

What is the major lethal toxin produced by all types of C. perfringens?

Answer 3

All types produce alpha toxin, which is a major lethal toxin.

Question 4

What are the two distinct diseases caused by C. perfringens?

Answer 4

gas gangrene
food poisoning

Question 5

what type of clostridium causes gas gangerene

Answer 5

Type A1

Question 6

what is gas gangrene associated with

Answer 6

War wounds
Automobile and motorcycle accidents
Septic abortions

Question 7

explain the pathogenesis of clostridium perfringens

Answer 7

~under aerobic conditions, C. perfringens multiplies
~ Then it produces alpha toxin (lecithinase) and other toxins which result in the rapid destruction of tissue carbohydrate with the production gas in decaying tissues
~septicemia can lead to intravascular hemolysis
~ Gas gangrene occurs following the infection of wounds, particularly tissue with a poor blood supply

Question 8

clinical manifestations of gas gangerene

Answer 8

• Pain, edema, cellulitis, and gangrene
  (necrosis) occur in the wound area
• Crepitation indicates the presence of gas in
  tissues.
• Hemolysis and jaundice are
  common, as are blood-tinged exudates.
• Shock and death can ensue.
• Mortality rates are high

Question 9

Lab diagnosis of clostridium perfringes

Answer 9

Specimens: Include material from wounds, necrotic tissue, and exudate.
* Smears of tissue and exudate samples show large gram-positive rods.
Spores are not usually seen because they are formed primarily under
nutritionally deficient conditions.
* The organisms are cultured anaerobically and then identified by sugar
fermentation reactions and organic acid production.
* C. perfringens colonies exhibit a double zone of hemolysis on blood agar.
* Egg yolk agar is used to demonstrate the presence of the lecithinase.
* Serologic tests are not useful.

Question 10

prevention of clostridium perfringes

Answer 10

1. Wounds should be cleansed and debrided.
2. Penicillin may be given for prophylaxis.
3. There is no vaccine

Question 11

treatment of clostridium perfringes A1

Answer 11

• Penicillin G is the antibiotic of choice.
• Wounds should be debrided. (Remove damaged tissue)