Type of test Stool
Normal findings
 Negative (no Clostridium toxin identified) , No other infectious agent identified
Test explanation and related physiology
 Clostridium difficile–associated disease (CDAD) bacterial infections usually affect the intestine (pseudomembranous coli tis) and often occur in patients who are immunocompromised or taking broad-spectrum antibiotics (e.g., clindamycin, ampicillin, cephalosporins). The disease can be community acquired, and the severity can range from mild nuisance diarrhea to severe pseudomembranous colitis and bowel perforation.
The infection possibly results from depression of the nor mal flora of the bowel caused by the administration of antibiotics. The clostridial bacterium produces two toxins (A and B) that cause inflammation and necrosis of the colonic epithelium. C. difficile can be diagnosed by obtaining colonic-rectal tissue for this toxin. Stool cultures for C. difficile can be performed but are also labor intensive and take longer to get results.
A rapid detection of C. difficile toxin B gene (tcdB) in human liquid or soft stool specimens is available. This method rapidly provides a definitive diagnosis of C. difficile. Quickly reaching a definitive diagnosis allows CDAD patients to get the proper treatment without delay and reduces hospital stays for inpatients with CDAD. At the same time, they can be placed in isolation sooner to reduce transmission and prevent outbreaks.
A positive PCR result for the presence of the gene-regulating toxin C production (tcdC) also indicates the presence of C. difficile and toxin A, B, or both.
Salmonella spp., Campylobacter spp., Shigella spp., Cryptosporidium spp., Escherichia coli, Vibrio spp., Yersinia spp., and Giardia lamblia may also cause acute diarrhea and can be identified in PCR multiplex panel testing. Viral infections caused by noro- or adenoviruses can also be detected on the newer stool testing panels.
Procedure and patient care
 Before
* Explain the method of stool collection to the patient. Be matter of fact to avoid embarrassment for the patient.
* Instruct the patient not to mix urine or toilet paper with the stool specimen.
• Handle the specimen carefully, as though it were capable of causing infection.
 During
* Instruct the patient to defecate into a clean container. A rectal swab cannot be used because it collects inadequate amounts of stool. The stool cannot be retrieved from the toilet.
• Stool can be obtained from incontinence pads.
• A stool specimen also can be collected by proctoscopy.
• Place the specimen in a closed container and transport it to the laboratory to prevent deterioration of the toxin.
• If the specimen cannot be processed immediately, refrigerate it (depending on laboratory protocol).
After
• Maintain enteric isolation precautions on all patients until appropriate therapy is completed.
Abnormal findings
Increased levels
- Antibiotic-related pseudomembranous colitis
- C. difficile colitis