Microorganisms and performance criteria for testing selective media 'CCA' for Enumeration of Escherichia coli en coliformen used in Water quality microbiology by comparing with a non-selective reference medium according to ISO 9308-1.
ISO 9308-1 (2014) medium: CCA
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1 Quantitative control of Productivity man
- Use a quantitative reference material or test suspension with a known number of Escherichia coli.
- Dilute this material so 50 to 120 cfu is inoculated on the CCA by membrane filtration method.
- Place the membrane on the surface of the agar under test (CCA).
- Do this also for the reference media (TSA).
- Incubate at (36 ± 2) °C for (21 to 24) h.
- Count the colonies on the medium under test (CCA) and the reference media (TSA).
- Calculate the productivity ratio PR. The criteria is: PR ≥ 0,7.
- If the PR exceeds 1,4 identify the reason.
- For this the total count of colonies obtained on the culture medium under test (CCA) is divided by the total count of colonies obtained on the defined reference medium (TSA).
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2 Quantitative control of Productivity man
- Use a quantitative reference material or test suspension with a known number of Citrobacter freundii.
- Dilute this material so 50 to 120 cfu is inoculated on the CCA by membrane filtration method for example 0.1 mL suspension.
- Place the membrane on the surface of the agar under test (CCA).
- Do this also for the reference media (TSA).
- Incubate at (36 ± 2) °C for (21 to 24) h.
- Count the colonies on the medium under test (CCA) and the reference media (TSA).
- Calculate the productivity ratio PR. The criteria is PR ≥ 0,7.
- If the PR exceeds 1,4 identify the reason.
- For this the total count of colonies obtained on the culture medium under test (CCA) is divided by the total count of colonies obtained on the defined reference medium (TSA).
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3 Quantitative control of Productivity man
- Use a quantitative reference material or test suspension with a known number of Enterobacter aerogenes.
- Dilute this material so 50 to 120 cfu is inoculated on the CCA by membrane filtration method for example 0.1 mL suspension.
- Place the membrane on the surface of the agar under test (CCA).
- Do this also for the reference media (TSA).
- Incubate at (36 ± 2) °C for (21 to 24) h.
- Count the colonies on the medium under test (CCA) and the reference media (TSA).
- Calculate the productivity ratio PR. The criteria is PR ≥ 0,7.
- If the PR exceeds 1,4 identify the reason.
- For this the total count of colonies obtained on the culture medium under test (CCA) is divided by the total count of colonies obtained on the defined reference medium (TSA).
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Qualitative control of Selectivity
- Use a reference material or test suspension with a known number of Enterococcus faecalis.
- Streak the test strain (Enterococcus faecalis) as a single line on the media under test (CCA).
- 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 (36 ± 2) °C for (21 to 24) h.
- Asses the amount of growth as, 0 for no growth, 1 for weak growth or 2 for good growth.
- For this medium (CCA) and standard (ISO 9308-1) combination the criteria is: "Total or partial inhibition.
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Qualitative control of Specificity
- Use a reference material or test suspension with a known number of Pseudomonas aeruginosa.
- Streak the test controlstrain (Pseudomonas aeruginosa) on the media under test (CCA) to obtain discrete colonies.
- Use a 1 µl loop in case of a concentration of at least 1000 cfu/mL.
- Incubate at (36 ± 2) °C for (21 to 24) h.
- Asses the presence, absence and/or grade of expression of biochemical responses and colony sizes and morphology.
- For this medium (CCA) and standard (ISO 9308-1) combination the characteristic reaction is: Colourless colonies.

Best Practice CCA
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 |
---|---|---|---|---|---|
Escherichia coli | or | TSA | (36 ± 2) °C for (21 to 24) h | PR ≥ 0,7 | Darkblue to violet colonies |
The best practice for Quantitative control of Productivity for media control of 'CCA' is based on the data displayed in this table according ISO 9308-1. |

Best Practice CCA
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 |
---|---|---|---|---|---|
Citrobacter freundii | TSA | (36 ± 2) °C for (21 to 24) h | PR ≥ 0,7 | Pink to red colonies | |
The best practice for Quantitative control of Productivity for media control of 'CCA' is based on the data displayed in this table according ISO 9308-1. |
Best Practice CCA
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 |
---|---|---|---|---|---|
Enterobacter aerogenes | TSA | (36 ± 2) °C for (21 to 24) h | PR ≥ 0,7 | Pink to red colonies | |
The best practice for Quantitative control of Productivity for media control of 'CCA' is based on the data displayed in this table according ISO 9308-1. |
Best Practice CCA
Qualitative control of Selectivity solid medium
Control strain | WDCM number | Ref. media | Incubation | Criteria | Characteristic reaction |
---|---|---|---|---|---|
Enterococcus faecalis | or | (36 ± 2) °C for (21 to 24) h | Total or partial inhibition | No growth | |
The best practice for Qualitative control of Selectivity for media control of 'CCA' is based on the data displayed in this table according ISO 9308-1. |
Best Practice CCA
Qualitative control of Specificity solid medium
Control strain | WDCM number | Ref. media | Incubation | Criteria | Characteristic reaction |
---|---|---|---|---|---|
Pseudomonas aeruginosa | (36 ± 2) °C for (21 to 24) h | Growth | Colourless colonies | ||
The best practice for Qualitative control of Specificity for media control of 'CCA' is based on the data displayed in this table according ISO 9308-1. |