Why should CAMP testing be incubated in ambient air?

• A. Staphylococcus aureus
• B. Group B Streptococcus
• C. Group A Streptococcus
• D. Group C Streptococcus

Answer: (C)

The CAMP test hinges on the CAMP factor produced by Group B Streptococcus interacting with the beta-hemolysin of Staphylococcus aureus to create an enhanced, crescent-shaped zone of hemolysis on blood agar where the two organisms meet. This reaction is temperature- and atmosphere-sensitive. Incubating in ambient air provides the environment that allows the CAMP interaction to manifest clearly; carbon dioxide in a CO2-rich incubator can dampen or distort the characteristic enhanced hemolysis, making results less reliable. By incubating in ambient air, the conditions are more favorable for the CAMP factor to exert its effect alongside the S. aureus beta-hemolysin, producing the distinct appearance that identifies Group B Streptococcus.