ISO 15213 (2003) medium: IS(“TS”)

Media control Food and animal feeding stuffs

Microorganisms and performance criteria for testing non-selective media 'IS("TS")' for Enumeration of Sulfite-reducing bacteria used in Food and animal feeding stuffs microbiology according to ISO 11133.

  • Quantitative control of Productivity

  • Black colonies. The characteristic reaction of  on IS(
    The characteristic reaction of Clostridium perfringens on IS("TS"): Black colonies.

    Best Practice IS("TS")

    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 IS("TS") by spreading for example 0.1 mL.
    3. Do this also for the reference media (A suitable nonselective medium for anaerobes).
    4. Incubate at (37 ± 1) °C for (24 ± 3) h to (48 ± 2) h.
    5. Count the colonies on the medium under test (IS("TS")) and the reference media (A suitable nonselective medium for anaerobes).
    6. Calculate the productivity ratio PR. The criteria is: PR ≥ 0,7.
    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 (IS("TS")) is divided by the total count of colonies obtained on the defined reference medium (A suitable nonselective 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 A suitable nonselective medium for anaerobes (37 ± 1) °C for (24 ± 3) h to (48 ± 2) h
    anaerobic atmosphere
    PR ≥ 0,7 Black colonies
    The best practice for Quantitative control of Productivity for media control of 'IS("TS")' is based on the data displayed in this table according ISO 11133.
  • Qualitative control of Specificity

  • No blackening. The characteristic reaction of  on IS(
    The characteristic reaction of Escherichia coli on IS("TS"): No blackening.

    Best Practice IS("TS")

    Qualitative control of Specificity solid medium

    1. Use a reference material or test suspension with a known number of Escherichia coli.
    2. Streak each test controlstrain (Escherichia coli) on the media under test (IS("TS")) to obtain discrete colonies.
    3. Use a 1 µl loop in case of a concentration of at least 1000 cfu/mL.
    4. Incubate at (37 ± 1) °C for (24 ± 3) h to (48 ± 2) h.
    5. Asses the presence, absence and/or grade of expression of biochemical responses and colony sizes and morphology.
    6. For this medium (IS("TS")) and standard (ISO 15213) combination the characteristic reaction is: No blackening.

    Control strain WDCM number Ref. media Incubation Criteria Characteristic reaction
    Escherichia coli or (37 ± 1) °C for (24 ± 3) h to (48 ± 2) h
    anaerobic atmosphere
    Growth No blackening
    The best practice for Qualitative control of Specificity for media control of 'IS("TS")' is based on the data displayed in this table according ISO 11133.