Stool for Shiga Toxin determination – Shipped May 13, 2019
ST1905-1: Negative ST1905-2: Positive ST1905-3: Negative
Suitability for Grading
A challenge is considered suitable for grading if agreement is reached by 80 percent of selected reference group and at least 70 percent of the participants.
Toxin detection was correctly performed by greater than 70 percent of all laboratories and was thus, determined to be suitable for grading.”
The samples are assessed for homogeneity and stability using in-house quality control methods and random selection of samples before and during production, and post sample delivery. The number of random samples selected is based on selection tables within Military standard 105E (1).
Sample ST1905-2 consisted of E.coli O157:H7, shiga toxin positive and was homogeneous and stable for 18 days. Samples ST1905-1 & 3 consisted of E.coli, non-O157:H7, shiga toxin negative and were homogeneous and stable for 33 days.
Grading of Shiga Toxin is based on a Positive / Negative result, no further statistical analysis is performed on the results beyond that described under “Suitability for grading.”
(1) Famum NR. Acceptance sampling. In: Modern Statistical Quality Control and Improvement. Belmont, California.: Duxbury Press; 1994:305.