ISO 7937 (2004) method: Clostridium perfringens

Process control Food and animal feeding stuffs

Horizontal method for the enumeration of Clostridium perfringens - Colony-count technique

  • 1 Quantitative process control with CRM-CP

  • Black colonies. The characteristic reaction of  on TSC (SC)
    Characteristic reaction: Black colonies.

    Best Practice

    The single strain CRM-CP contains Clostridium perfringens spores which are not heat-resistant. This material can only be used for vegetative cell analyse

    1. Use a quantitative reference material (CRM-CP) with a known number of Clostridium perfringens.
    2. Defrost the material at room temperature for 30 minutes.
    3. Mix well before use and dilute the material so countable numbers are inoculated on the media (TSC (SC)) by spread plate method.
    4. Best results are obtained when a practicable range of 80 cfu to 120 cfu per plate with a minimum number of 50 cfu per plate is used.
    5. Incubate at (37 ± 1) °C for (20 ± 2) h.
    6. Count the colony forming units and register in a control chart.
    7. The characteristic reaction is: Black colonies.

    Kind of reference material Biosisto product for this control method Control Strain WDCM number
    Single-strain reference material Clostridium perfringens 00007
    The Biosisto reference material in this table is used in the best practice for Quantitative process control according ISO 17025.
  • 2 Quantitative process control with RM-CP veg

  • Black colonies. The characteristic reaction of  on TSC (SC)
    Characteristic reaction: Black colonies.

    Best Practice

    The single strain RM-CP veg contains Clostridium perfringens vegetative cells and heat-resistant spores. This material can be used for vegetative cell analyse and the spore analyse

    1. Use a quantitative reference material (RM-CP veg) with a known number of Clostridium perfringens.
    2. Defrost the material at room temperature for 30 minutes.
    3. Mix well before use and dilute the material so countable numbers are inoculated on the media (TSC (SC)) by spread plate method.
    4. Best results are obtained when a practicable range of 80 cfu to 120 cfu per plate with a minimum number of 50 cfu per plate is used.
    5. Incubate at (37 ± 1) °C for (20 ± 2) h.
    6. Count the colony forming units and register in a control chart.
    7. The characteristic reaction is: Black colonies.

    Kind of reference material Biosisto product for this control method Control Strain WDCM number
    Single-strain reference material Clostridium perfringens 00007
    The Biosisto reference material in this table is used in the best practice for Quantitative process control according ISO 17025.