Technical reference
doesn't count bacteria directly. It asks what concentration would be most likely to produce this pattern of positive tubes, so its answer is a statistical estimate.
Parameters
| Best used for | Low concentrations, below 100/g; milk, water, particulate foods |
|---|---|
| Assumptions | Random distribution; separate cells; independent tubes; one viable cell gives growth |
| Common design | 3 tubes each at 0.1, 0.01, 0.001 g |
| Example | 0, 0, 1 positive: 3.0 (0.15 to 9.6) |
| Top of the 3-tube table | 3, 3, 3 positive: more than 1,100 |
Records that prove it
- Dilutions and inocula
- Positive tubes per dilution
- Confirmation results
- MPN with 95 percent confidence limits
CCP or prerequisite?
That depends on the for your process. The number, if it has one, belongs to your plan.