ISO 14189 (2016) medium: TSC

Media control Water quality 

Microorganisms and performance criteria for testing selective media 'TSC' for Enumeration of Clostridium perfringens used in Water quality  microbiology by comparing with a non-selective reference medium according to ISO 14189.

  • Quantitative control of Productivity

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

    Best Practice TSC

    Best result when Bloodagar is used as reference medium. An overlay ensures black coloration of the colonies

    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 by membrane filtration method.
    3. Place the membrane on the surface of the agar under test (TSC).
    4. Do this also for the reference media (TSA or blood agar).
    5. Incubate at (44 ± 1) °C for (21 ± 3) h.
    6. Count the colonies on the medium under test (TSC) and the reference media (TSA or blood agar).
    7. Calculate the productivity ratio PR. The criteria is: PR ≥ 0,5.
    8. If the PR exceeds 1,4 identify the reason.
    9. For this the total count of colonies obtained on the culture medium under test (TSC) is divided by the total count of colonies obtained on the defined reference medium (TSA or blood agar).
    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
    00080 opt
    00174 opt
    		 TSA or blood agar (44 ± 1) °C for (21 ± 3) h
    anaerobic atmosphere    		 PR ≥ 0,5 Black colonies
    The best practice for Quantitative control of Productivity for media control of 'TSC' is based on the data displayed in this table according ISO 14189.

  • Qualitative control of Selectivity

    • Best Practice TSC

    Qualitative control of Selectivity solid medium

    1. Use a reference material or test suspension with a known number of Bacillus subtilis subsp. spizizenii.
    2. Streak the test strain (Bacillus subtilis subsp. spizizenii) as a single line on the media under test (TSC).
    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 (44 ± 1) °C for (21 ± 3) 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) and standard (ISO 14189) combination the criteria is: "Total inhibition (0).

    Control strain WDCM number Ref. media Incubation Criteria Characteristic reaction
    Bacillus subtilis subsp. spizizenii
    		(44 ± 1) °C for (21 ± 3) h
    anaerobic atmosphere    		 Total inhibition (0) No growth
    The best practice for Qualitative control of Selectivity for media control of 'TSC' is based on the data displayed in this table according ISO 14189.