When determining a concentration of microorganisms within a test sample using a technique which involves counting individual bacterial colonies or colony forming units (CFU) on a test plate, there is a possibility that the concentration observed on the test plate may exceed the upper countable limit of the test.
In such situations where a value cannot be provided the result may be reported as Too Numerous to Count, or TNTC.
In some regions a greater than result might be reported for this scenario. For example >200 CFU/100 mL is used to indicate an over populated plate count where the upper countable limit can not be determined.
