ISO 7937 (2004) medium: TSC (SC)

Media control Food and animal feeding stuffs

Microorganisms and performance criteria for testing selective media 'TSC (SC)' for Enumeration of Clostridium perfringens used in Food and animal feeding stuffs microbiology according to ISO 11133.

  • Quantitative control of Productivity

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

    Best Practice TSC (SC)

    Quantitative control of Productivity solid medium

    1. Use a quantitative reference material or test suspension with a known number of Clostridium perfringens.
    2. Dilute this material so 50 to 120 cfu is inoculated on the TSC (SC).
    3. Do this also for the reference media (TSA or other non-selective medium for anaerobes).
    4. Incubate at (37 ± 1) °C for (20 ± 2) h.
    5. Count the colonies on the medium under test (TSC (SC)) and the reference media (TSA or other non-selective medium for anaerobes).
    6. Calculate the productivity ratio PR. The criteria is: PR ≥ 0,5.
    7. If the PR exceeds 1,4 identify the reason.
    8. For this the total count of colonies obtained on the culture medium under test (TSC (SC)) is divided by the total count of colonies obtained on the defined reference medium (TSA or other non-selective medium for anaerobes).
    Calculate the productivity ratio PR as follows: PR  NS
    N0
    Ns = total count test medium
    N0 = total count reference medium

    Control strain WDCM number Ref. media Incubation Criteria Characteristic reaction
    Clostridium perfringens TSA or other non-selective medium for anaerobes (37 ± 1) °C for (20 ± 2) h
    anaerobic atmosphere
    PR ≥ 0,5 Black colonies
    The best practice for Quantitative control of Productivity for media control of 'TSC (SC)' is based on the data displayed in this table according ISO 11133.
  • Qualitative control of Selectivity

  • Best Practice TSC (SC)

    Qualitative control of Selectivity solid medium

    1. Use a reference material or test suspension with a known number of Escherichia coli.
    2. Streak the test strain (Escherichia coli) as a single line on the media under test (TSC (SC)).
    3. Use a 1 µl loop in case of a concentration of at least 10000 cfu or a 10 µl loop in case of a concentration between 1000 and 10000 cfu.
    4. Incubate at (37 ± 1) °C for (20 ± 2) h.
    5. Asses the amount of growth as, 0 for no growth, 1 for weak growth or 2 for good growth.
    6. For this medium (TSC (SC)) and standard (ISO 7937) combination the criteria is: "Total inhibition (0).

    Control strain WDCM number Ref. media Incubation Criteria Characteristic reaction
    Escherichia coli or (37 ± 1) °C for (20 ± 2) h
    anaerobic atmosphere
    Total inhibition (0) No growth
    The best practice for Qualitative control of Selectivity for media control of 'TSC (SC)' is based on the data displayed in this table according ISO 11133.