Clostridium Difficile Nucleic Acid Amplified Test with reflex to Toxin Confirmation 
Mnemonic C DIF RFLX
CPT 87493
Test Code  
Synonyms C diff, C. difficile Toxin Assay, Pseudomembranous Colitis Toxin Assay, Antibiotic-associated Colitis Toxin Assay, C. diff
Test Includes Polymerase Chain Reaction (PCR) test for the qualitative detection of toxin producing Clostridium difficile. If PCR is positive, antigen testing will occur to confirm the presence of toxins
Specimen Unformed (liquid or soft) stool
Volume Unformed stool: 3.0 mL
Container Stool Transport Vial WITHOUT perservatives (Para Pak white-capped clean vial)
Special Instructions Do not freeze specimen. Do not submit formed stool (specimen must be liquid or soft, taking the shape of the container).
Specimen Prep Collect at least 5 mL of liquid or soft stool and place in a sterile collection vial without preservative (Para Pak white-capped clean vial). Refrigerate specimen.
Storage Refrigerate
Transport Temp Refrigerated
Stability Rm Temp 24 hours
Stability Refrig 72 hours
Stability Frozen Unacceptable
Methodology Polymerase Chain Reaction (PCR) and Enzyme Immunoassay
Rejection Criteria Formed stool specimen, specimen received in preservative, frozen specimen, leaking specimen, rectal swab, specimens tested within the past 7 days 
Reference Value Negative 
Performed/TAT Monday - Sunday   2-8 Hours    
Comments Only one specimen per patient per 7 days will be accepted. This test should not be performed on asymptomatic patients. This test should not be used as a “test of cure”. “Cure” is clinical. Do not submit any additional specimens within 7 days. Do not submit any additional specimens for the duration admission for a positive test. Formed stool specimens are not acceptable for testing. Infants have been shown to be asymptomatic carriers of toxigenic C. difficile. Testing should not be performed on asymptomatic infants under one year of age. Specimens from infants under one year of age will be rejected, but will be saved. The Microbiology laboratory must be notified (414-805-7570) within 5 days if extenuating circumstances exist that would warrant testing. Please call the Microbiology laboratory to discuss testing on infant specimens. All new positive results on hospital inpatients are called.