clostridial myonecrosis

Question 1

case

Answer 1

chronic intravenous drug use presented to the emergency department with right upper limb pain and swelling lasting 24 hours.severe
edema of the upper limb, erythema, blistering of the arm
and crepitus over the shoulder and arm was noted.

Question 2

Specimen:

Answer 2

Necrotic tissues, muscle fragments and exudates from deeper parts of the wound

Question 3

Direct microscopy:

Answer 3

Thick, stubby, boxcar-shaped Gram-positive bacilli without spore

Question 4

Culture:

Answer 4

➢ Robertson cooked meat broth, egg yolk agar, etc.
➢ Incubation: Anaerobically (by GasPak or Anoxomat, etc.)
On blood agar - Target hemolysis (double zone hemolysis)- complete: θ-toxin, incomplete: alpha toxin

Question 5

biochem

Answer 5

➢ Reverse CAMP test: Positive
➢ Heat tolerance test: Positive (45oC for 4–6 hours)
*Nagler’s reaction: C. perfringens produces an opalescence surrounding the streak line on egg yolk agar or media containing 20% human serum (due to lecithinase activity of α-toxin).
➢ Opalescence can be inhibited by incorporating anti-α-toxin to the medium
In litmus milk: Produces stormy clot reaction.