Principle, Uses, Procedure, And Result Interpretation: CAMP Test

Scientists all around the world will use various tests to determine results for various experiments, hypotheses, etc. The CAMP test is one of them.

Principle, Uses, Procedure, And Result Interpretation: CAMP Test

This test is used to distinguish Streptococcus agalactiae from another classification of the streptococci (Group B) – the Streptococcus S. agalactiae. 

In this article, we will discuss the principle, uses, and procedures of the CAMP test, as well as the ways you can interpret the results.

 So, if you need to understand the CAMP test for research purposes, or you just have a general interest in how it works, then read on for more. 

History Of The CAMP Test 

The CAMP test was first introduced in 1944. It was established by three researchers, Christie, Atkins, and Munch-Petersen.

The word “CAMP” in “CAMP test” is an acronym for their names, although many people often mistake “Munch-Petersen” for two people, and two separate last names, instead of one. 

The CAMP test used in this context should not be confused with the cAMP test, the test for Cyclic adenosine monophosphate. The two tests have no relationship. 

What Is The Principle Of The CAMP Test?

A CAMP factor, or more specifically a diffusible extracellular hemolytic heat-stable protein, is produced by the organism B streptococci, as well as many other organisms. 

This CAMP factor and the Staphylococcus aureus (beta-lysin) interact which results in enhanced lysis of red blood cells in the body. 

B. streptococci are placed in a streaked line perpendicular way to the S. aureus streak when on the agar of sheep blood. Where the two lines come close together you will see a positive reaction that looks like the head of an arrow of hemolysis. 

This activity of the beta-hemolysin is made by the majority of Staphylococcus aureus strains and is enhanced by the group B streptococci’s extracellular protein.

If any beta-hemolysin has this factor then any interaction with it will cause something called synergistic hemolysis, which can be seen on an agar plate. 

This is observed with both group B streptococci non-hemolytic and hemolytic isolates. 

What Are The Uses Of The CAMP Test?

Here are some of the uses of the CAMP test!

  • Identification of Listeria monocytogenes
  • Distinguish Streptococcus agalactiae from beta-hemolytic Streptococcus. 

What Is The Procedure Of The CAMP Test?

Let’s take a closer look at the procedure for the CAMP test. 

  • First, you need to take an agar plate of sheep’s blood and streak a strain of aureus that produces beta-lysin down the middle of the plate. The steak should be around 3-4 cm in length. 
  • Now, you need to streak the test organisms across the plate. Make sure they are in a perpendicular line to the first streak, and within 2mm. 
  • Now, you should incubate the organisms at around 28.4 degrees F or 35-37 degrees C. Leave them for eighteen to twenty-four hours in ambient air.
  • The streptococci (Group B) and some of the beta-streptococci will produce a visible enhancement of the activity of B-lysin in the aureus strain of the organism.

CAMP Test: Result Interpretation

CAMP Test: Result Interpretation  

Here are some interpretations you can take from the results

  • Positive Result: Any sign of enhanced hemolysis will be shown with results shaped like an arrowhead in the beta-hemolysis. You will see it at the intersection of both organisms. 
  • Negative Result: With a negative result, there will be no sign of hemolysis enhancement. 

Is There A Quality Control For CAMP Tests?

Yes, there is quality control for CAMP tests. Let’s check them out below. 

  • Positive Result: Enhanced hemolysis (head of an arrow shape), Streptococcus agalactiae (ATCC13813)
  • Negative Result:  Beta-hemolysis with no enhanced arrowhead, Streptococcus pyogenes (ATTCC19615.)

Are There Any Limitations To The CAMP Test?

Yes, like many tests in science, there are limitations to the CAMP test. Let’s review these in more detail below. 

  • A tiny percentage of the streptococci (group A) may still experience a positive reaction to the CAMP test.
  • Some Streptococcal (Group A) will bring back a positive CAMP test result if the plate is incubated incorrectly. For example, if the plate is placed in incubation conditions that are anaerobic. 
  • You can only use sheep’s blood for the CAMP test. Other types of blood will not result in a proper reaction. 
  • If you leave the CAMP test organisms in the incubation period for too long or elevate the temperatures of the incubation atmosphere then this may give a false reading. 
  • Listeria monocytogene colonies have a very narrow section of beta-hemolysis on an agar plate. It is easily confused with the beta-hemolysis streptococci (group B).

Final Thoughts

The CAMP test was first established in 1944 by three researchers, Christie, Atkins, and Munch-Petersen.

The purpose of the CAMP test is to distinguish the species Streptococcus agalactiae from another classification of the Lancefield Group B streptococci – the Streptococcus S. agalactiae. 

This is tested using a sheep’s blood agar plate. A  streak of the aureus strain that produces beta-lysin is placed down the center of the plate. Then, the test organism is streaked across the plate in a perpendicular line to the first. 

After the incubation period, the test is checked for results. A positive result for the CAMP test will result in an arrowhead in the beta-hemolysis, while a negative result will not show signs of enhancement. 

Like many other tests, there are limitations to the CAMP test. This is why you must ensure you follow the procedure correctly to yield the most accurate results. 

Jennifer Dawkins

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