Stool: Clostridium difficile common antigen and toxin/toxin gene

CT161A: Negative/Negative      CT161B: Positive/Positive      .

Reference Laboratories:

CT161A: 12/12 labs reported C. difficile common antigen/gene/toxin negative/negative, negative/NT or NT/negative

CT161B: 12/12 labs reported C. difficile common antigen/gene/toxin positive/positive, positive/NT or NT/positive

Participants’ Results

Table 1. CT161-A - Antigen/Toxin or Toxin geneTotalGrade
Negative / Negative408/8
Negative / NT54/4
NT / Negative94/4
Positive / Positive10/8
NT due to temporary closure1ungraded

Table 2. CT161-B - Antigen/Toxin or Toxin geneTotalGrade
Positive / Positive458/8
Negative / Negative10/8
NT / Positive94/4
NT due to temporary closure1ungraded
Total 56

Table 3. CT161B - IC /PH NotificationTotalGrade


NT: not tested

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.

Antigen and toxin detection was correctly performed by at least 80 percent of reference laboratories and greater than 70 percent of all laboratories thus, both challenges were determined to be suitable for grading.

Maximum grade: CT161A: 8 , CT161B: 12

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).

The challenge sample lot was confirmed to be homogeneous and stable for at least 50 days.

Grading of Clostridium difficile common antigen and toxin/toxin gene detection 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.

Posted in Clostridium difficile Results