Microorganisms and performance criteria for testing selective media 'mCCDA' for Enumeration of Campylobacter used in Food chain microbiology according to ISO 10272-2.
ISO 10272-2 (2017) medium: mCCDA
Media control Food chain
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Quantitative control of Productivity - Use a quantitative reference material or test suspension with a known number of Campylobacter jejuni.
- Dilute this material so 50 to 120 cfu is inoculated on the mCCDA by spreading for example 0.1 mL.
- Do this also for the reference media (Blood agar).
- Incubate at (41,5 ± 1) °C for (44 ± 4) h.
- Count the colonies on the medium under test (mCCDA) and the reference media (Blood agar).
- Calculate the productivity ratio PR. The criteria is: PR ≥ 0,5.
- If the PR exceeds 1,4 identify the reason.
- For this the total count of colonies obtained on the culture medium under test (mCCDA) is divided by the total count of colonies obtained on the defined reference medium (Blood agar).
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1 Qualitative control of Selectivity
- Use a reference material or test suspension with a known number of Escherichia coli.
- Streak the test strain (Escherichia coli) as a single line on the media under test (mCCDA).
- 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.
- Incubate at (41,5 ± 1) °C for (44 ± 4) h.
- Asses the amount of growth as, 0 for no growth, 1 for weak growth or 2 for good growth.
- For this medium (mCCDA) and standard (ISO 10272-2) combination the criteria is: "Total or partial inhibition (0-1).
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2 Qualitative control of Selectivity opt
- Use a reference material or test suspension with a known number of Staphylococcus aureus.
- Streak the test strain (Staphylococcus aureus) as a single line on the media under test (mCCDA).
- 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.
- Incubate at (41,5 ± 1) °C for (44 ± 4) h.
- Asses the amount of growth as, 0 for no growth, 1 for weak growth or 2 for good growth.
- For this medium (mCCDA) and standard (ISO 10272-2) combination the criteria is: "Total inhibition (0)".
Best Practice mCCDA
Quantitative control of Productivity solid medium
| 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 |
|---|---|---|---|---|---|
| Campylobacter jejuni | or | Blood agar | (41,5 ± 1) °C for (44 ± 4) h microaerobic atmosphere |
PR ≥ 0,5 | Greyish, flat and moist colonies, sometimes with metallic sheen |
| Campylobacter coli | |||||
| The best practice for Quantitative control of Productivity for media control of 'mCCDA' is based on the data displayed in this table according ISO 10272-2. | |||||
Best Practice mCCDA
Qualitative control of Selectivity solid medium
| Control strain | WDCM number | Ref. media | Incubation | Criteria | Characteristic reaction |
|---|---|---|---|---|---|
| Escherichia coli | or | (41,5 ± 1) °C for (44 ± 4) h microaerobic atmosphere |
Total or partial inhibition (0-1) | No characteristic colonies | |
| The best practice for Qualitative control of Selectivity for media control of 'mCCDA' is based on the data displayed in this table according ISO 10272-2. | |||||
Optional Selectivity Control Method for extra, additional control. The use of an optional method alone does not meet the standard.
Best Practice mCCDA
Qualitative control of Selectivity solid medium
| Control strain | WDCM number | Ref. media | Incubation | Criteria | Characteristic reaction |
|---|---|---|---|---|---|
| Staphylococcus aureus | (41,5 ± 1) °C for (44 ± 4) h microaerobic atmosphere |
Total inhibition (0) | No growth | ||
| The best practice for Qualitative control of Selectivity for media control of 'mCCDA' is based on the data displayed in this table according ISO 10272-2. | |||||
