CAMP Test: Principle, Procedure, Results, and Uses

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Many of the biochemical tests are identified and followed to test the ability of the micro- organisms to survive in the particular media. One such test is known as CAMP test.

CAMP test is usually used to identify the Group B- Beta hemolytic Streptococci based on their formation of a substance known as CAMP factor, which enlarges the area of hemolysis formed by the Beta-hemolysin elaborated from Staphylococcus aureus.

CAMP Factor

CAMP factor is a diffusible, and a heat stable protein that is produced by a group B- Streptococci.

This test is considered as one of the synergistic tests between the two species of Staphylococcus namely S. aureus and S. agalactiae S. agalaciae produces the CAMP factor and S. aureus produces the sphingomyelin C, which has the capability to bind with the membranes of the red blood cells.

What is CAMP Test?

Camp test is usually done to distinguish the species of Streptococcus agalacctieae from other species of the Beta-hemolytic species of Streptococcus.

Streptococci agalactiae is one of the members of the Lance field Group B Streptococci It is also considered as one of the causative agents of mastitis in cows.

CAMP is simply an acronym of the authors of this test namely Christie, Atkinson, Munch, and Peterson. They identified this test in the year 1944.

CAMP Test Objective

 The main aim of the test is to differentiate the Species of Streptococcus agalactiae from the other Beta-hemolytic species of Streptococci

 To determine the ability of the organism of an organism to produce the camp factor

CAMP Test Principle

Streptococcus agalactiae usually synthesis a diffusible and a thermostable, extracellular protein which interacts synergistically with the Beta-hemolysin that is produced by Staphylococcus aureus, and results in the formation of a Zone which enhances the lysis of the sheep or bovine erythrocytes.

In Standard CAMP tests elaboration of two toxins relies n the growth which forms a typical arrowhead or a flame shaped clearing the the interaction point of the two organisms and it is streaked perpendicular to each other.

The rapid disks helps us in utilizing the extract of the staphylococcal Beta-hemolysin which interacts directly with the CAMP factor that already left diffused in the medium around the colony of Streptococcus agalactiae.

Thus, the hemolysis produced from the Beta-hemolytic strains of the Staphylococcus aureus is enhanced but one of the extracellular proteins which is produced by the species of Group-B- streptococcus.

The interaction between the S. aureus and the CAMP factor of the Group B streptococci results in the formation of the Synergistic hemolysis which thus results in the formation of the arrowhead done of the hemolysis.

Thus, this test is very useful for identifying the S. agalactiace and many other Gram- positive rods including Listeria monocytogenes.

CAMP Test Requirements


 Blood agar


 Beta-lysin reagent

 Culture of aureus

 Disks containing Beta-lysin of aureus


 Sterile wooden applicator

 Bacteriologic loops

 Distilled water

 Petri dish and slide

CAMP Test Procedure

The CAMP test is usually performed in two ways, either by using Standard method or by using Disk method.

1. Standard Method

Initially a streak of Beta-lysin that produces strain of S.aureus is put down at the center of the sheep blood agar plate.

It should be made clear that the streak should be only at a length of 3 to 4 cm.

The streak test organism is put across the agar plate, perpendicular to the streak at the length of about 2mm or even less than that.

Then the agar plate is let to incubate at a temperature of about 35 to 37ºC in an ambient air for about 18 to 24 hours.

After incubation the enhancement of Beta-lysin aureus strain is seen which is produced by Group B streptococci and other species of Beta-streptococci.

2. Disk Method

Here the disk is removed from the vial and it is placed on the warm Blood agar plate.

Then the micro-organism is streaked there, from the edge of the disk, for about 2 to 3mm.

Then the plate is incubated at a temperature of about 35 degree Celsius for a whole night in the carbon dioxide incubator.

CAMP Test Quality Control
Streptococcus agalactiaeIt is usually for about 24 to 48 hours at a temperature of about 33 to 37ºC in the air having 5% of carbon dioxide.It is considered as CAMP positive, as the formation of arrowhead hemolysis is seen at a the intersect ion of the streaks.
Streptococcus pyrogensThe culture is incubated for about 24 to 48 hours at a temperature of about 33 to 37ºC in an air contain 5% of carbon dioxide.Here the results are considered as CAMP negative, as Beta-hemolysis does not form a 3nchnaced arrow head.
CAMP Test Result

 A position results in the standard method is concluded by the formation of the distinct arrowhead of the hemolysis at the interaction of the two streaks made from Streptococcus and the test organism.

 Whereas, the Positive reverse CAMP or phospholipase D is shown by a typical arrowhead or formation of no hemolysis at the junction o the two hemolytic organisms.

 In case, of the Disk test, a positive result is detected by distinct arc shaped done, of the complete hemolysis at the point of the junction, with the Beta lysin and the test organism.

 A lack of enhanced hemolysis near the colony is being tested as the negative result.

CAMP Test Citations


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