--- title: "Reverse CAMP Test: Principle, Procedure, Results and Uses" description: "Get Free Biology Notes" url: https://biologynotesonline.com/reverse-camp-test/ --- # Reverse CAMP Test: Principle, Procedure, Results and Uses Learn the reverse CAMP test principle, procedure and result, including bow-tie hemolysis in Clostridium perfringens, positive organisms, uses and CAMP test differences. The **reverse CAMP test** is a phenotypic microbiological test used mainly for the presumptive identification of *Clostridium perfringens*. In the classical test, *C. perfringens* is streaked near a CAMP-positive strain of *Streptococcus agalactiae* on blood agar. Interaction between the bacterial extracellular factors produces a characteristic zone of enhanced hemolysis, often described as a **bow-tie or arrowhead-shaped reaction**. **Used mainly for:** Presumptive identification of *Clostridium perfringens* and demonstration of characteristic hemolytic interactions. **Quick facts** FeatureAnswerMain test organism*Clostridium perfringens*CAMP-factor producer*Streptococcus agalactiae*MediumBlood agar, commonly sheep blood agarMain reactionSynergistic enhanced hemolysisPositive appearanceBow-tie / arrowhead-shaped enhanced hemolysisInterpretationPresumptive evidence supporting identification of *C. perfringens* ## What is Reverse CAMP Test? **Reverse CAMP test** is a biochemical test used for the presumptive identification of *Clostridium perfringens*. It is based on the synergistic hemolytic reaction produced between *Clostridium perfringens* and group B *Streptococcus agalactiae* on blood agar. In this test, the suspected organism and *Streptococcus agalactiae* are streaked at right angles to each other on a blood agar plate. A positive reverse CAMP reaction is seen by an **arrow-shaped or bow-tie zone of enhanced hemolysis** near the junction of the two organisms. Thus, this reaction can be used for rapid presumptive identification of *C. perfringens*. ## Objectives of Reverse CAMP Test - To presumptively identify ***Clostridium perfringens*** by detecting its characteristic enhanced hemolytic reaction with group B ***Streptococcus agalactiae***. - To differentiate ***C. perfringens*** from other related *Clostridium* species based on the positive **reverse CAMP reaction**. ## Principle of the Reverse CAMP Test The **Reverse CAMP test** is based on the synergistic hemolysis produced by the alpha toxin of *Clostridium perfringens* and the **CAMP factor** produced by *Streptococcus agalactiae*. The alpha toxin of *C. perfringens* is a phospholipase C which acts on the membrane phospholipids of erythrocytes. This makes the erythrocytes more susceptible to the hemolytic action of CAMP factor. When *C. perfringens* and *S. agalactiae* are streaked at right angles to each other on blood agar, their extracellular products diffuse through the medium. At the area where these products interact, increased destruction of red blood cells takes place. This produces a characteristic **arrow-shaped or bow-tie zone of enhanced hemolysis** near the junction of the two bacterial streaks. ![Reverse CAMP test principle showing Clostridium perfringens and Streptococcus agalactiae producing enhanced hemolysis on blood agar](https://biologynotesonline.com/wp-content/uploads/2026/03/reverse-camp-test-principle-1024x768.png)Reverse CAMP test principle showing Clostridium perfringens and Streptococcus agalactiae producing enhanced hemolysis on blood agar ### Synergistic Hemolysis in Clostridium perfringens *C. perfringens* produces **alpha toxin (phospholipase C)** which has hemolytic activity. *S. agalactiae* produces CAMP factor. When these two factors meet in the blood agar, their combined action produces stronger hemolysis than that produced by either factor alone. This is referred to as **synergistic hemolysis** and forms the basis of a positive reverse CAMP reaction. ![Principle of Reverse CAMP test](https://biologynotesonline.com/wp-content/uploads/2025/12/Principle-of-Reverse-CAMP-test-.png)Principle of Reverse CAMP test ## Materials Required for the Reverse CAMP Test The following are the materials required for performing the **Reverse CAMP test**– - **[Sheep blood agar](https://biologynotesonline.com/sheep-blood-agar-composition-principle-procedure-uses/) plate** containing about 5% sheep blood. - Pure culture of the suspected *Clostridium perfringens*. - CAMP-positive culture of *Streptococcus agalactiae* (group B Streptococcus). - Sterile inoculating loop or inoculating needle. - **[Anaerobic jar](https://biologynotesonline.com/mcintosh-and-fildes-anaerobic-jar-principle-parts-procedure/) or anaerobic incubation system** for maintaining anaerobic condition. - Incubator maintained at about 35–37°C. The plate is incubated anaerobically to allow the growth of *C. perfringens*. ![Procedure of Reverse CAMP Test](https://biologynotesonline.com/wp-content/uploads/2025/12/Procedure-of-Reverse-CAMP-Test-.png)Procedure of Reverse CAMP Test ## Reverse CAMP Test Procedure The following are the steps for performing the **Reverse CAMP test**– ### Plate Inoculation - Take a fresh sheep blood agar plate. - A CAMP-positive culture of *Streptococcus agalactiae* is streaked in a straight line along the center of the blood agar plate. - The suspected culture of *Clostridium perfringens* is streaked at right angle to the streak of *S. agalactiae*. - The two streaks should not touch each other. A small gap of about **1–2 mm** is maintained between the streaks. - This arrangement allows the extracellular products produced by both organisms to diffuse and interact in the agar. ### Incubation and Plate Examination - The inoculated blood agar plate is incubated **anaerobically at 37°C for about 18–24 hours**. - After incubation, the area between the perpendicular streaks is examined for enhanced hemolysis. - A positive reaction is indicated by the formation of a characteristic **arrowhead or bow-tie shaped zone of enhanced hemolysis** at the interaction zone between *C. perfringens* and *S. agalactiae*. - Absence of this characteristic synergistic hemolysis is considered as a negative reverse CAMP reaction. ## Reverse CAMP Test Results ![Results of Reverse CAMP Test](https://biologynotesonline.com/wp-content/uploads/2025/12/Results-of-Reverse-CAMP-Test-.png)Results of Reverse CAMP Test The **Reverse CAMP test** is interpreted by observing the hemolysis formed at the interaction zone between *Clostridium perfringens* and *Streptococcus agalactiae*. The characteristic enhanced hemolysis indicates a positive reaction. ### Positive Reverse CAMP Test A positive Reverse CAMP test shows an **arrowhead-shaped or bow-tie zone of enhanced hemolysis** near the junction of the two bacterial streaks. This enhanced hemolysis is produced due to the synergistic reaction between *C. perfringens* and group B *S. agalactiae*. It is considered as a characteristic positive reaction of *C. perfringens*. ### Negative Reverse CAMP Test In a negative reaction, the characteristic enhanced hemolysis is absent at the interaction zone. No arrowhead or bow-tie shaped enhancement is formed between the two streaks. Several other *Clostridium* species may show a negative Reverse CAMP reaction, while most clinical isolates of *C. perfringens* are positive. ![Positive and negative reverse CAMP test showing bow-tie enhanced hemolysis](https://biologynotesonline.com/wp-content/uploads/2026/03/reverse-camp-test-positive-negative-result-1024x768.png)Positive and negative reverse CAMP test showing bow-tie enhanced hemolysis **Reverse CAMP Test Quick Interpretation** ResultPlate appearanceInterpretationExample organism**Positive enhanced hemolysis**Bow-tie or arrowhead-shaped enhanced hemolysis at the interaction zone**Reverse CAMP reaction present***Clostridium perfringens***Negative**No characteristic enhancement of hemolysis at the interaction zoneReverse CAMP reaction not demonstratedNegative isolate/control ![reverse camp test result](https://biologynotesonline.com/wp-content/uploads/2021/06/reverse-camp-test-1024x576.jpg)Reverse Christie, Atkins, Munch-Petersen (CAMP) test. Arcanobacterium haemolyticum is streaked on a blood agar plate. Staphylococcus aureus is then streaked perpendicular to the Arcanobacterium path. A positive reverse CAMP test result is indicated (arrow). ## Reverse CAMP Positive Organisms The following are the important organisms that show a **positive Reverse CAMP reaction**– - ***Clostridium perfringens*** – It is the classical Reverse CAMP-positive organism. It produces an arrowhead or bow-tie shaped zone of enhanced hemolysis when grown near *Streptococcus agalactiae*. Most isolates of *C. perfringens* show this characteristic reaction. - ***Arcanobacterium haemolyticum*** – It can also show a positive Reverse CAMP reaction with *Streptococcus agalactiae*. The hemolysis produced by *S. agalactiae* is enhanced near the growth of *A. haemolyticum*. This reaction can be used as one of the tests for its identification. ## Organism-Specific Reverse-CAMP-Type Reactions Test organismPartner organismRelevant factorObserved reactionIdentification significance*Clostridium perfringens**Streptococcus agalactiae***Alpha toxin (phospholipase C)** of *C. perfringens* with CAMP factorArrowhead or bow-tie shaped **enhanced hemolysis** is produced at the interaction zone.It is the classical Reverse CAMP reaction used for presumptive identification of *C. perfringens*.*Arcanobacterium haemolyticum**Streptococcus agalactiae***Phospholipase D (PLD)** of *A. haemolyticum* and CAMP-associated hemolytic activityEnhanced hemolysis is produced near *S. agalactiae*.A positive reverse CAMP-type reaction is useful for identification of *A. haemolyticum*. Its PLD is different from the alpha toxin involved in *C. perfringens*.*Corynebacterium pseudotuberculosis**Staphylococcus aureus***Phospholipase D (PLD)** produced by *C. pseudotuberculosis* and staphylococcal beta-hemolysin**Inhibition of hemolysis** occurs in the interaction area rather than the enhanced hemolysis typical of *C. perfringens*.The phospholipase D reaction is useful as a phenotypic characteristic of *C. pseudotuberculosis*. Thus, this reverse-CAMP-type reaction should not be interpreted by the same mechanism as the *C. perfringens* reaction. ## CAMP Test vs Reverse CAMP Test **CAMP test** and **Reverse CAMP test** are blood agar based tests which are used for presumptive identification of bacteria by observing characteristic hemolytic interaction between two organisms. The major differences between CAMP test and Reverse CAMP test are as follows- [View Post↗](https://biologynotesonline.com/reverse-camp-test/) CharacteristicsCAMP TestReverse CAMP TestMain organism identifiedIt is mainly used for identification of ***Streptococcus agalactiae*** (group B Streptococcus).It is mainly used for presumptive identification of ***Clostridium perfringens***.Indicator organismBeta-hemolytic ***Staphylococcus aureus*** is used.CAMP-positive ***Streptococcus agalactiae*** is used.Factor produced by test organism*S. agalactiae* produces **CAMP factor**.*C. perfringens* produces **alpha toxin (phospholipase C)**.PrincipleCAMP factor of *S. agalactiae* acts synergistically with beta-lysin produced by *S. aureus*.Alpha toxin of *C. perfringens* acts synergistically with CAMP factor produced by *S. agalactiae*.Streaking pattern*S. aureus* is generally streaked at the center and suspected *S. agalactiae* is streaked perpendicular to it without touching.*C. perfringens* and *S. agalactiae* are streaked at right angles with a small gap between the two streaks.IncubationThe plate is generally incubated at **35°C for about 24 hours in ambient air**.The plate is incubated under **anaerobic conditions** for proper growth of *C. perfringens*.Positive reactionAn **arrowhead-shaped zone of enhanced beta-hemolysis** is formed near the junction, with the arrow pointing towards the *S. aureus* streak.A characteristic **bow-tie, reversed arrow or arrow-shaped zone of enhanced hemolysis** is formed at the interaction zone.Major useIt helps to differentiate *S. agalactiae* from *Streptococcus pyogenes* and other non-group B streptococci.It helps in presumptive identification of *C. perfringens* from other related *Clostridium* species. ## Common Interpretation Errors The following are some of the common errors during interpretation of the **Reverse CAMP test**– - Normal hemolysis around the bacterial growth should not be considered as a positive reaction. A positive Reverse CAMP test requires a clear **zone of enhanced hemolysis at the interaction area** between *Clostridium perfringens* and *Streptococcus agalactiae*. - The result should not be interpreted only from the direction of the arrowhead. The positive reaction may appear as an **arrow-shaped or bow-tie zone of enhanced hemolysis**, depending on the arrangement of the two streaks. The enhanced interaction zone is more important for interpretation. - A negative Reverse CAMP test does not completely exclude *C. perfringens*. About **96–97%** of the tested *C. perfringens* isolates were positive in earlier evaluations, therefore occasional isolates can show a negative reaction. - A positive result should not be considered as final identification of *C. perfringens*. Reverse CAMP test is a **presumptive identification test**, and the result should be considered together with other characteristics or confirmatory identification methods. - Hemolysis away from the junction of the two organisms should not be confused with synergistic hemolysis. The characteristic reaction is examined where the extracellular products of *C. perfringens* and group B *S. agalactiae* interact on the blood agar plate. ## Uses of the Reverse CAMP Test The following are some of the important uses of the **Reverse CAMP test**– - It is used for the rapid presumptive identification of ***Clostridium perfringens*** isolated from clinical and other specimens. - It is used to differentiate *C. perfringens* from other related *Clostridium* species based on its characteristic positive reverse CAMP reaction. - It can be used as an additional phenotypic test for identification of suspected *C. perfringens* colonies after their isolation in the laboratory. The positive organism produces a characteristic zone of enhanced hemolysis with *Streptococcus agalactiae*. - It is also used to demonstrate the **synergistic hemolysis** produced by *C. perfringens* and the CAMP factor of *S. agalactiae* on blood agar. ## Advantages of Reverse CAMP test The following are some of the important advantages of the **Reverse CAMP test**– - It is a useful test for the **presumptive identification** of ***Clostridium perfringens*** from clinical isolates. - The test has good sensitivity. About **96–97%** of *C. perfringens* isolates were reported to produce a positive Reverse CAMP reaction in earlier studies. - The positive reaction is generally easy to observe. A characteristic **arrow-shaped or bow-tie zone of enhanced hemolysis** is formed at the interaction area. - It helps in differentiation of *C. perfringens* from several other *Clostridium* species which show a negative Reverse CAMP reaction. - The test is based on growth and hemolytic reaction on blood agar and does not require complex molecular detection methods. It can therefore be used as a practical phenotypic test during routine identification of suspected *C. perfringens*. ## Limitations of the Reverse CAMP Test The following are some of the important limitations of the **Reverse CAMP test**– - The Reverse CAMP test provides only **presumptive identification** of *Clostridium perfringens*. Other identification tests may be required for definite confirmation of the organism. - Not all strains of *C. perfringens* give a positive reaction. Studies have reported about **96–97%** of the tested isolates as Reverse CAMP positive, therefore a small number of strains can give a negative reaction. - The test requires a suitable CAMP-positive culture of *Streptococcus agalactiae* and sheep blood agar. Improper growth or arrangement of the bacterial streaks can affect development of the characteristic hemolytic zone. - **Anaerobic incubation** is required for proper growth of *C. perfringens*. Thus, an anaerobic culture system is necessary while performing the test. - Reverse CAMP reaction is not completely restricted to *C. perfringens*. Some other bacteria such as *Arcanobacterium haemolyticum* can also enhance hemolysis with *S. agalactiae*. Therefore, the reaction should be interpreted together with colony morphology, Gram staining and other identification tests. ## FAQs on Reverse CAMP Test **What is reverse CAMP test?** **Reverse CAMP test** is a biochemical test used for presumptive identification of ***Clostridium perfringens***, ***Arcanobacterium haemolyticum***, and some other reverse CAMP positive bacteria. **What is reverse CAMP test principle?** It is based on interaction between hemolytic toxin or phospholipase of test organism and hemolytic factor produced by indicator organism on sheep blood agar. **Which bacteria are reverse CAMP positive?** Important reverse CAMP positive bacteria are ***Clostridium perfringens***, ***Arcanobacterium haemolyticum***, and ***Corynebacterium pseudotuberculosis***. **What is reverse CAMP test positive result?** Positive result is seen as bow-tie or reversed arrowhead hemolysis in ***Clostridium perfringens***. In ***Arcanobacterium haemolyticum***, it may show arrow of no hemolysis with ***Staphylococcus aureus***. **What is the difference between CAMP test and reverse CAMP test?** In CAMP test, the test organism usually produces CAMP factor. In reverse CAMP test, the suspected organism produces toxin or phospholipase which reacts with CAMP factor or beta hemolysin of another organism. **Why is reverse CAMP test used for *****Clostridium perfringens*****?** It is used because ***Clostridium perfringens*** produces alpha toxin which acts with CAMP factor of ***Streptococcus agalactiae*** and gives characteristic bow-tie or reversed arrowhead hemolysis. **What is CAMP inhibition test?** **CAMP inhibition test** is a form of reverse CAMP reaction where the test organism inhibits beta hemolysin of ***Staphylococcus aureus*** and produces an arrow of no hemolysis. **What is arrowhead zone of hemolysis?** Arrowhead zone of hemolysis is a triangular zone of enhanced clearing on blood agar formed due to synergistic action of bacterial hemolytic factors. ## References - American Society for Microbiology. (2009). 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