2013 ISPAM Mid-Year Mtg Book

The relevant performance characteristics for method verification of a quantitative microbiological method are:

-Intralaboratory reproducibility (intermediate precision); -Measurement uncertainty (U); - Repeatability (s r ); -Trueness (bias).

These performance characteristics vary according to the sample matrix and in user laboratories. Therefore each user laboratory shall determine these performance characteristics in relevant matrices that are routinely tested. The performance characteristics determined shall meet the specifications established in the validation study. 8.2 Number of samples and replicates tested For intralaboratory reproducibility and measurement uncertainty (and repeatability), the study design is based on ISO/TS 19036. This has been modified to include matrix effects when samples are spiked. For the study, 10 samples are required. Only 1 representative strain of the target micro-organism is required to spike samples. Samples can be inoculated using commercial products that are fit for this purpose (e.g. lyophilized pellets EZ-CFU, Lenticules, Bioballs etc). Inoculation is carried out as described in Figure 1. If possible, the levels of contamination of samples shall cover the range of the method. At least 3 levels of contamination should ?or shall be used. Test the samples according to the method to be verified and the reference method (where necessary). Testing shall be carried out on 10 different?occasions or days and shall be performed by at least 2 technicians working independently and with separate samples and reagents.