Clostridium difficile toxin gene

Test ID: 

705721

CPT code:

87493

Synonyms:

Clostridium difficile Toxin Gene, NAA

Clinical 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.

Test 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 Type:

Stool (unformed)

Requested Volume: 

5 g

Minimum Volume: 

0.5 g or 0.5 mL liquid stool

Container Type: 

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.

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.

Rejection Criteria

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