Success! In Clinical Laboratory Science – Bacteriology Practice Test

The test relies on a characteristic interaction between Clostridium perfringens and Staphylococcus aureus in blood agar that reveals its identity quickly. C. perfringens makes an alpha-toxin (lecithinase) that, when placed near S. aureus, alters the pattern of hemolysis to produce a distinct reverse CAMP appearance. In a reverse CAMP setup, you streak the unknown anaerobe perpendicular to a streak of S. aureus; if the unknown is C. perfringens, you’ll see enhanced hemolysis on the side opposite the S. aureus line, forming a recognizable pattern that points to this organism. This makes it the most appropriate presumptive test for identifying C. perfringens. Esculin hydrolysis isn’t specific for C. perfringens and is used for other groups of organisms; cytotoxin assays are more specialized and not routine presumptive tests for this identification; SPS sensitivity isn’t a standard method for identifying C. perfringens.