What is the minimum number of C. perfringens organisms per gram in food required for diagnosis?

• A. ≥100,000 organisms/g
• B. ≥1,000 organisms/g
• C. ≥10,000,000 organisms/g
• D. ≥10 organisms/g

Answer: (A)

The amount of C. perfringens in food needed to implicate it as the source of illness is tied to the infectious dose. For C. perfringens food poisoning, a relatively large number of organisms in the food is typically required to cause illness and to be considered diagnostic evidence of contamination. The commonly used threshold is about 100,000 organisms per gram of food. Counts at this level or higher in the reported food strongly support it as the source of illness, whereas much lower counts are not reliable for diagnosis. So the minimum number that meets this diagnostic criterion is 100,000 organisms per gram.