Clostridium perfringens type A is the most common cause of gas gangrene in traumatic and post-surgical wound infections. Which medium is used for presumptive identification of C. perfringens based on the characteristic stormy clot reaction with vigorous lactose fermentation and acid production?
- A Robertson cooked meat medium (milk coagulation and gas) ✓
- B MacConkey agar (colorless colonies)
- C Thioglycollate broth (strict anaerobe growth)
- D Campylobacter blood-free selective agar
Correct answer: A. Robertson cooked meat medium (milk coagulation and gas)
Explanation
Milk medium (litmus milk) shows a stormy clot reaction with C. perfringens due to rapid lactose fermentation producing acid and gas that disrupt the clot. Robertson cooked meat medium also supports growth and shows saccharolytic change, but the stormy clot test is classically described in milk medium. MacConkey agar is selective for Gram-negative organisms. Thioglycollate is a general enrichment medium without a specific presumptive identification feature for this organism.
Reference: Mackie & McCartney Practical Medical Microbiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.