CAMP test

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This is an example of a positive CAMP test indicated by the formation of an arrowhead where the Strep group B (Streptococcus agalactiae) meets the Staphylococcus aureus (light-yellow/golden middle streak).

The CAMP test is a test to identify group B β-hemolytic streptococci (Streptococcus agalactiae)[1][2] based on their formation of a substance (CAMP factor[3]) that enlarges the area of hemolysis formed by the β-hemolysin elaborated from Staphylococcus aureus.

CAMP factor[edit]

Although the test is usually used to identify group B streptococcus, there is some evidence that the CAMP factor gene is present in several groups of streptococci, including group A.[4]

A similar factor has been identified in Bartonella henselae.[5]


The CAMP test can be used to identify Streptococcus agalactiae. Though not strongly beta-hemolytic on its own,[6] group B strep presents with wedge-shaped colonies in the presence of Staphylococcus aureus.[7]

It can also be used to identify Listeria monocytogenes which produces a positive CAMP reaction.[8]


  1. Streak a beta-lysin–producing strain of aureus down the center of a sheep blood agar plate.
  2. The test organism streak should be 3 to 4 cm long.
  3. Streak test organisms across the plate perpendicular to the S. aureus streak within 2 mm. (Multiple organisms can be tested on a single plate).
  4. Incubate at 35°-37°C in ambient air for 18-24 hours.
  5. Wedge shaped pattern radiating from the test organism near the S. aureus indicates positivity


CAMP is an acronym for "Christie–Atkins–Munch-Petersen",[9][10][11] for the three researchers who discovered the phenomenon.[12]

It is often incorrectly reported as the product of four people (counting Munch-Petersen as two people).[13] The true relationship (three people) is the reason for two en dashes and then one hyphen in Christie–Atkins–Munch-Petersen.

The name of the test bears no relationship to the name of the second messenger cyclic adenosine monophosphate (commonly referred to as cAMP).


  1. ^ Phillips EA, Tapsall JW, Smith DD (August 1980). "Rapid tube CAMP test for identification of Streptococcus agalactiae (Lancefield group B)". J. Clin. Microbiol. 12 (2): 135–7. PMC 273541. PMID 7014603.
  2. ^ Wilkinson HW (July 1977). "CAMP-disk test for presumptive identification of group B streptococci". J. Clin. Microbiol. 6 (1): 42–5. PMC 274694. PMID 328534.
  3. ^ "Laboratory Demonstrations". Archived from the original on September 28, 2008. Retrieved 2008-12-12.
  4. ^ Gase K, Ferretti JJ, Primeaux C, McShan WM (September 1999). "Identification, cloning, and expression of the CAMP factor gene (cfa) of group A streptococci". Infect. Immun. 67 (9): 4725–31. PMC 96801. PMID 10456923.
  5. ^ Litwin CM, Johnson JM (July 2005). "Identification, cloning, and expression of the CAMP-like factor autotransporter gene (cfa) of Bartonella henselae". Infect. Immun. 73 (7): 4205–13. doi:10.1128/IAI.73.7.4205-4213.2005. PMC 1168562. PMID 15972511.
  6. ^ "Microbiology Primer: Hemolysis". Archived from the original on 2008-12-11. Retrieved 2008-12-12.
  7. ^ "Streptococcaceae Answers". Archived from the original on 2008-10-05. Retrieved 2008-12-12.
  8. ^ Aryal, Sagar. "CAMP Test- Principle, Uses, Procedure and Result Interpretation". Microbiology Retrieved 2019-09-04.
  9. ^ Ratner HB, Weeks LS, Stratton CW (August 1986). "Evaluation of spot CAMP test for identification of group B streptococci". J. Clin. Microbiol. 24 (2): 296–7. PMC 268893. PMID 3528214.
  10. ^ Nsagha DS, Bello CS, Kandakai-Olukemi YT (January 2000). "Hippurate hydrolysis and Christie, Atkins, Munch-Peterson tests as epidemiological diagnostic tools for Streptococcus agalactiae carriage in pregnancy". East Afr Med J. 77 (1): 34–6. doi:10.4314/eamj.v77i1.46373. PMID 10944837.
  11. ^ Valanne S, McDowell A, Ramage G, et al. (May 2005). "CAMP factor homologues in Propionibacterium acnes: a new protein family differentially expressed by types I and II". Microbiology. 151 (Pt 5): 1369–79. doi:10.1099/mic.0.27788-0. PMID 15870447.
  12. ^ Christie, R., Atkins, NE and Munch-Petersen, E. (1944). A note on a lytic phenomenon shown by group B streptococci. Aust. J. Exp. Biol. Med. Sci. 22, 197-200
  13. ^ "Streptococci". Retrieved 2008-12-12.