CT1911

Stool: Clostridium difficile common antigen and toxin/toxin gene

CT1911A: negative/negative  CT1911B: positive/positive

CMPT QA/QC

CT1911-A: C.difficile common antigen negative and gene/toxin negative, viable for 40 days

CT1911-B: C.difficile common antigen positive and gene/toxin positive, viable for 40 days

Reference Laboratories

CT1911-A: 9/12 labs reported common Antigen/Toxin or Toxin gene negative/negative, 3 labs reported not tested/negative

CT1911-B: 9/12 labs reported common Antigen/Toxin or Toxin gene positive/positive, 3 labs reported not tested/positive

Participants’ results

NOTE: grading for Clostridium difficile toxin testing has changed. Please click here for more details

(Insert table results A) 

Table 1. CT1911A - Antigen/Toxin or Toxin geneTotalGrade
negative/negative47Acceptable/Acceptable
not tested/negative or negative/not tested8Ungraded/Acceptable or Acceptable/Ungraded
positive/positive2Unacceptable/Unacceptable
Total57

Insert table IC/PH A if applicable [table “x” not found /]

(Insert table results B) 

Table 3. CT1905B - Antigen/Toxin or Toxin geneTotalGrade
positive/positive50Acceptable/Acceptable
not tested/positive 5Ungraded/Acceptable
negative/negative2Unacceptable/Unacceptable
Total57

Insert table IC/PH B if applicable 

Table 4. CT1905B - IC /PH NotificationTotalGrade
Yes54Acceptable
No3Unacceptable
Total57

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.

Grading: Please note that grading for Clostridium difficile toxin testing has changed. Please click here for more details

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 40 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.

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