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Lab update: New C. diff protocol begins

03 Mar 2019

Reflex toxin testing to positive C. diff tests



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Salem Health Laboratories began a new testing protocol on Feb. 18 for patients who develop gastrointestinal problems. Please note: There is no need for providers to order additional tests.

After treatment with antibiotics, many patients develop problems ranging from mild diarrhea to severe pseudomembranous colitis. Many cases of the milder forms and most cases of PMC are caused by toxigenic strains of C. diff — an opportunistic anaerobic bacterium that grows in the intestine once antibiotics have altered the normal flora.

Toxigenic strains of C. diff carry the genes encoding the toxins. Disease onset is associated when toxins are produced. Not all toxigenic strains of C. diff will produce toxin.

We will continue the current PCR-based testing. The order code has been updated to reflex to the toxin test when indicated. Toxin testing will be performed daily and resulted by 8 a.m. The expected turnaround time after the test will be four to 24 hours for the toxin result. Positive PCR results will continue to be called to the ordering source or provider. Toxin results will not be called. The toxin test is only offered as a reflex test for positive or invalid PCR tests. It cannot be ordered as a stand-alone.

 

PCR-NAAT LAB7105

Toxin A/B

Sensitivity

95-100%

78-86%

NPV

99.8%

98.1%

PCR-NAAT testing statistics are based on prescreening for appropriate testing. When these guidelines are not followed, false positives can be detected.

Questions? Contact Renee Gerros at 503-814-1640 or Julie Koch at 503-814-2783.