CAMP Test: Definition, Principle, Uses, Results

The CAMP test, also known as the CAMP co-hemolysis test, is a test used for the presumptive identification of Streptococcus agalactiae.

◉ what is CAMP test?

The CAMP test has been widely used in diagnostic microbiology since its discovery in 1944 by Christie et al. for the presumptive identification of Streptococcus agalactiae, a major pathogen of neonatal infections.

The CAMP reaction is a co-hemolysis phenomenon manifested by an area of strong hemolysis when Streptococcus agalactiae, which produces the CAMP factor, is seeded next to Staphylococcus aureus, which secretes sphingomyelinase, on sheep blood agar.

The term "CAMP" is an acronym formed from the names of the authors of this test (Christie, Atkinson, Munch and Peterson).

CAMP is an acronym for the authors of this test (Christie, Atkinson, Munch, Peterson).

◉ Principle of CAMP test

◉ Procedure and results

The CAMP test is performed on standard dishes of sheep blood agar or trypticase soy agar +5% sheep blood.

◉ Results : A positive test CAMP appears as an area of arrowhead hemolysis adjacent to where the two lines of streaks come together. A lack of enhanced hemolysis near the colony being tested is a negative CAMP test

◉ CAMP test for the identification of Listeria monocytogenes

In 1962, Fraser, G. was the first to observe the synergistic lysis of sheep red blood cells by L. monocytogenes and S. aureus or Rhodococcus equi.

The CAMP test can be used to differentiate hemolytic Listeria species; L. monocytogenes, L. ivanovii and L. seeligeri.

Hemolysis by L. monocytogenes and to a lesser degree L. seeligeri is enhanced in the vicinity of S. aureus and hemolysis by L. ivanovii is enhanced in the vicinity of the R. equi streak (cholesterol oxidase). Listeria factors responsible for synergistic lysis of red blood cells with S. aureus and Rhodococcus. equi are respectively PLC and LLO (Listeriolysin O).

Note : The CAMP test has been reviewed for its applicability and it has been shown that sometimes it cannot properly differentiate between L. monocytogenes and L. ivanovii

◉ Results : A CAMP test positive appears as a smaller, less obvious rectangular area of hemolysis

◉ The reverse CAMP test

A reverse CAMP reaction is a reaction whereby hemolysis by beta-hemolysin of Staphylococcus aureus (or S. intermedius) is inhibited by the production of phospholipase D (or phospholipase C).

◉ Results : A positive reverse CAMP test appears as An arrow without hemolysis forms at the junction of the test organism with staphylococci. Ex : Corynebacterium pseudotuberculosis , Corynebacterium ulcerans , Arcanobacterium haemolyticum , Mycoplasma hyorhinis , C. perfringens

CAMP test

CAMP test positive(S.agalactiae, Listeria.spp, A.haemolyticum)

◉ Notes

◉ Conclusion

The CAMP test remains a valuable tool in diagnostic microbiology. By examining the phenomenon of co-hemolysis, it aids in the presumptive identification of Streptococcus agalactiae, a significant pathogen in neonatal infections.

It is important to note that additional examinations are essential to establish an accurate diagnosis.


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  5. Standardization and evaluation of the CAMP reaction for the prompt, presumptive identification of Streptococcus agalactiae (Lancefield group B) in clinical material
  6. Characterization of Streptococcus agalactiae CAMP Factor as a Pore-forming Toxin
  7. Crystal structure of the Streptococcus agalactiae CAMP factor provides insights into its membrane-permeabilizing activity
  8. Revision of the validity of CAMP tests for Listeria identification. Proposal of an alternative method for the determination of haemolytic activity by Listeria strains
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