Purpose

The Christie, Atkins, and Munch-Peterson (CAMP) test is used to differentiate group B streptococci (Streptococcus agalactiae positive) from other streptococcal species. Listeria monocytogenes also produces a positive CAMP reaction.

Principle

 Certain organisms (including group B streptococci) produce a diffusible extracellular hemolytic protein (CAMP factor) that acts synergistically with the beta-lysin of Staphylococcus aureus to cause enhanced lysis of red blood cells. The group B streptococci are streaked perpendicular to a streak of S. aureus on sheep blood agar. A positive reaction appears as an arrowhead zone of hemolysis adjacent to the place where the two streak lines come into proximity.

Method

1. Streak a beta-lysin–producing strain of S. aureus down the center of a sheep blood agar plate.

 2. Streak test organisms across the plate perpendicular to the S. aureus streak within 2 mm. (Multiple organisms can be tested on a single plate).

3. Incubate overnight at 35°-37°C in ambient air.

Expected Results

Positive: Enhanced hemolysis is indicated by an arrowhead-shaped zone of beta hemolysis at the juncture of the two organisms (Figure 1, A).

Negative: No enhancement of hemolysis (Figure 1, B).

Limitations

A small percentage of group A streptococci may have a positive CAMP reaction. The test should be limited to colonies with the characteristic group B streptococci morphology and narrow zone beta-hemolysis on sheep blood agar.

Quality Control

 Positive: Streptococcus agalactiae (ATCC13813)—enhanced arrowhead hemolysis Negative: Streptococcus pyogenes (ATCC19615)—beta-hemolysis without enhanced arrowhead formation

Fig1. CAMP test. A, Positive; arrowhead zone of beta-hemolysis (at arrow), typical of group B streptococci. B, Negative; no enhancement of hemolysis.

مواضيع ذات صلة

Clostridium difficile (C. diff, Clostridial toxin assay)

Chromosome karyotype (Blood chromosome analysis, Chromosome studies, Cytogenetics, Karyotype)

Aminotransferases

Creatine Kinase (CK)

Chlamydia

Ceramides

Bile Esculin Test

carboxyhemoglobin (COHb, Carbon monoxide)

Calcitonin (Human calcitonin [HCT], Thyrocalcitonin), Procalcitonin (PCT)

Bronchoscopy

Breast cancer tumor analysis (DNA ploidy status, S-phase fraction, Cathepsin D, HER-2 [c erbB2, neu] protein, p53 protein, Ki67 protein)

Bacitracin Susceptibility