A Gram-positive bacillus with boxcar arrangement, reverse CAMP positive and double-zone beta-hemolysis. Identify the organism.

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Multiple Choice

A Gram-positive bacillus with boxcar arrangement, reverse CAMP positive and double-zone beta-hemolysis. Identify the organism.

This pattern points to Clostridium perfringens. The boxcar-shaped Gram-positive bacilli in long parallel chains are characteristic of clostridia, and among them C. perfringens is well known for producing a distinctive double-zone beta-hemolysis on blood agar due to its lecithinase (alpha toxin) activity—an inner zone of complete hemolysis with a surrounding zone of partial hemolysis. The reverse CAMP reaction is a supportive test used to identify this organism in the lab, helping distinguish it from other Gram-positive rods. Putting these clues together—the boxcar-like rods, the double-zone beta-hemolysis, and the reverse CAMP positivity—points to Clostridium perfringens.

This pattern points to Clostridium perfringens. The boxcar-shaped Gram-positive bacilli in long parallel chains are characteristic of clostridia, and among them C. perfringens is well known for producing a distinctive double-zone beta-hemolysis on blood agar due to its lecithinase (alpha toxin) activity—an inner zone of complete hemolysis with a surrounding zone of partial hemolysis. The reverse CAMP reaction is a supportive test used to identify this organism in the lab, helping distinguish it from other Gram-positive rods. Putting these clues together—the boxcar-like rods, the double-zone beta-hemolysis, and the reverse CAMP positivity—points to Clostridium perfringens.

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