Test Details
Methodology
Real-time polymerase chain reaction (PCR)
Result Turnaround Time
1 - 2 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
Aid in the diagnosis of antibiotic-associated diarrheal disease and pseudomembranous colitis. Toxigenic C difficile is a major cause of antibiotic-associated diarrhea and colitis and is the causative agent for virtually all cases of pseudomembranous colitis. Although about 2% of normal healthy adults are colonized with C difficile, many patients acquire this organism through nosocomial infection. Exposure to most antibiotics is thought to allow proliferation of toxigenic C difficile by disrupting the normal intestinal flora. Two large toxin proteins, toxin A and toxin B, encoded by two separate genes, named tcdA and tcdB, are believed to be the primary virulence factors of C difficile. Together, with three additional genes, they form a 19.6-kb pathogenicity locus called PaLoc, which is found in all known toxigenic strains of C difficile.
Limitations
• This test does not distinguish between viable and nonviable organisms.
• The association of C difficile with disease in infants under the age of two is not well understood. Infants in this age group are frequent carriers of toxigenic C difficile and can have toxin present without symptoms of the disease.
• Test results are to be used in conjunction with information available from the patient's clinical evaluation and other diagnostic procedures.
• This test is for use with unformed (ie, soft, loose) stool samples only.
• This test detects/presumptively differentiates the BI/NAP1/027 strain from other toxigenic strains of C difficile. Detection of BI/NAP1/027 strains of C difficile is presumptive and is solely for epidemiological purposes and is not intended to guide or monitor treatment for C difficile infections.
• The detection of bacterial nucleic acid is dependent on proper specimen collection and handling (including transportation and storage).
Custom Additional Information
During the last several years, increased rates of C difficile infection have been reported, noting more severe disease and an associated increase in mortality. C difficile infection remains a disease mostly associated with health care (at least 80%), with the elderly remaining at greatest risk. More disease has been reported in traditionally "low-risk" individuals, such as healthy persons in the community and peripartum women. Severe disease outbreaks of C difficile infection in health care facilities have been attributed to the emergence of a hypervirulent epidemic strain, known by its names—assigned by various typing schemes—as restriction enzyme analysis type BI, North American Pulsed Field type 1 (NAP1), or PCR ribotype 027. BI/NAP1/027 has spread widely, and it appears more virulent due to its increased production of toxins A and B and its production of an additional toxin known as binary toxin. This strain is also believed to produce more spores, leading to enhanced persistence in the environment.
Specimen Requirements
Specimen
Stool (unformed)
Volume
5 g
Minimum Volume
0.5 g or 0.5 mL liquid stool
Container
Sterile screw-cap container or stool transport without preservatives (Para-Pak® white clean vial). "Cool Whip" containers, denture cups, or other similar containers often leak or even explode during transport and may be rejected by the laboratory.
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 5 days (stability provided by manufacturer or literature reference) |
Reference Range
Negative
Storage Instructions
Specimen should be kept at 2°C to 8°C and transported to the laboratory within 24 hours of collection. Do not freeze.
Causes for Rejection
Unlabeled specimen or name discrepancy between specimen and test request label; quantity insufficient; formed stools; frozen stool; stool in preservative; specimens other than stool; improper storage or transport device; grossly leaking specimens; specimen older than 24 hours that is stored at room temperature, or specimen older than five days stored at 2°C to 8°C
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 183988 | C difficile Toxin Gene NAA | 54067-4 | 183989 | C difficile Toxin Gene NAA | 54067-4 | |
| Order Code | 183988 | |||||
| Order Code Name | C difficile Toxin Gene NAA | |||||
| Order Loinc | 54067-4 | |||||
| Result Code | 183989 | |||||
| Result Code Name | C difficile Toxin Gene NAA | |||||
| UofM | ||||||
| Result LOINC | 54067-4 |