Reverse CAMP is a laboratory test used to identify Clostridium perfringens, a bacterium responsible for gas gangrene and food poisoning. It's based on the synergistic interaction between a specific toxin produced by C. perfringens and the CAMP factor, typically associated with Streptococcus agalactiae.
Here's a breakdown:
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CAMP Test Basics: The classic CAMP (Christie, Atkins, Munch-Petersen) test identifies Streptococcus agalactiae (Group B Strep). S. agalactiae produces the CAMP factor, a diffusible protein.
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The Synergistic Effect: The CAMP factor enhances the lysis of red blood cells (hemolysis) caused by beta-lysin produced by Staphylococcus aureus. This creates a characteristic arrowhead-shaped zone of enhanced hemolysis on a blood agar plate when S. agalactiae is streaked perpendicularly to a streak of S. aureus.
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Reverse CAMP Principle: In the reverse CAMP test, Clostridium perfringens takes the place of S. aureus. Instead of beta-lysin, C. perfringens produces alpha-toxin (phospholipase C). The CAMP factor (typically produced by a Streptococcus species) then synergistically enhances the hemolytic activity of C. perfringens' alpha-toxin.
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How it Works in Practice:
- A streak of a known CAMP factor-producing organism (often Streptococcus agalactiae, though other CAMP-positive organisms can be used) is made on a blood agar plate.
- The unknown bacterium (suspected C. perfringens) is streaked perpendicularly to the Streptococcus streak, but does not touch it.
- The plate is incubated anaerobically (since Clostridium is an anaerobe).
- If the unknown organism is C. perfringens, a "bow-tie" or arrowhead-shaped zone of enhanced hemolysis will appear at the intersection of the two streaks. This indicates a positive reverse CAMP test.
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Why is it Useful? While other tests can identify C. perfringens, the reverse CAMP test provides a relatively simple and rapid confirmatory method.
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Summary: The reverse CAMP test uses the synergistic interaction between the CAMP factor and the alpha-toxin of Clostridium perfringens to identify the bacterium, showing enhanced hemolysis on a blood agar plate. It's a valuable tool in clinical microbiology.
