Council Directive 98/83/EC (1998) medium: mCP

Media control Water quality 

Microorganisms and performance criteria for testing selective media 'mCP' for Enumeration of Clostridium perfringens used in Water quality  microbiology by comparing with a non-selective reference medium according to ISO 11133.

  • 1 Quantitative control of Productivity

  • Best Practice mCP

    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 mCP.
    3. Use the same method of inoculation as described in the specific individual Council Directive 98/83/EC.
    4. Do this also for the reference media (TSA or other nonselective medium for anaerobes).
    5. Incubate at (44 ± 1) °C for (21 ± 3) h.
    6. Count the colonies on the medium under test (mCP) and the reference media (TSA or other nonselective medium for anaerobes).
    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 (mCP) is divided by the total count of colonies obtained on the defined reference medium (TSA or other 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 TSA or other nonselective medium for anaerobes (44 ± 1) °C for (21 ± 3) h
    anaerobic atmosphere
    PR ≥ 0,5 Yellow colonies; Phophatase test positive
    The best practice for Quantitative control of Productivity for media control of 'mCP' is based on the data displayed in this table according ISO 11133.
  • 2 Quantitative control of Productivity

  • Best Practice mCP

    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 mCP.
    3. Use the same method of inoculation as described in the specific individual Council Directive 98/83/EC.
    4. Do this also for the reference media (Media batch mCP already validated).
    5. Incubate at (44 ± 1) °C for (21 ± 3) h.
    6. Count the colonies on the medium under test (mCP) and the reference media (Media batch mCP already validated).
    7. Calculate the productivity ratio PR. The criteria is PR ≥ 0,7.
    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 (mCP) is divided by the total count of colonies obtained on the defined reference medium (Media batch mCP already validated).
    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 Media batch mCP already validated (44 ± 1) °C for (21 ± 3) h
    anaerobic atmosphere
    PR ≥ 0,7 Yellow colonies; Phophatase test positive
    The best practice for Quantitative control of Productivity for media control of 'mCP' is based on the data displayed in this table according ISO 11133.
  • Qualitative control of Selectivity

  • Best Practice mCP

    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 (mCP).
    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 (mCP) and standard (Council Directive 98/83/EC) combination the criteria is: "Total inhibition (0).

    Control strain WDCM number Ref. media Incubation Criteria Characteristic reaction
    Escherichia coli or (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 'mCP' is based on the data displayed in this table according ISO 11133.
  • Qualitative control of Specificity

  • Best Practice mCP

    Qualitative control of Specificity solid medium

    1. Use a reference material or test suspension with a known number of Clostridium bifermentas.
    2. Streak the test controlstrain (Clostridium bifermentas) on the media under test (mCP) to obtain discrete colonies.
    3. Use a 1 µl loop in case of a concentration of at least 1000 cfu/mL.
    4. Incubate at (44 ± 1) °C for (21 ± 3) h.
    5. Asses the presence, absence and/or grade of expression of biochemical responses and colony sizes and morphology.
    6. For this medium (mCP) and standard (Council Directive 98/83/EC) combination the characteristic reaction is: Blue colonies; Phosphatase test negative.

    Control strain WDCM number Ref. media Incubation Criteria Characteristic reaction
    Clostridium bifermentas (44 ± 1) °C for (21 ± 3) h
    anaerobic atmosphere
    Growth Blue colonies; Phosphatase test negative
    The best practice for Qualitative control of Specificity for media control of 'mCP' is based on the data displayed in this table according ISO 11133.