Decoding CDI: How is C. difficile Diagnosed?
Decoding CDI: How is C. difficile Diagnosed?
The Diagnostic Journey
Diagnosing Clostridioides difficile infection (CDI) can be tricky, but understanding the tests involved can help demystify the process.
Contents
- The Gold Standard: NAAT
- Other Testing Methods
- When is Testing Needed?
The Gold Standard: NAAT
The nucleic acid amplification test (NAAT) is a highly sensitive method used to detect the presence of C. difficile toxins in stool samples. This test can quickly identify the infection and is often combined with enzyme immunoassays to ensure accuracy. However, it cannot differentiate between active infections and carriers of the bacteria.
Other Testing Methods
Enzyme immunoassays for toxins A and B provide another way to diagnose CDI. Although less sensitive than NAAT, they are quick and can confirm the presence of toxins. Selective anaerobic culture is another method, though it's slower and more labor-intensive, primarily used for research purposes.
When is Testing Needed?
Testing is crucial for patients with unexplained diarrhea and relevant risk factors like antibiotic use. Only liquid stool samples from symptomatic patients should be tested to avoid false positives. In cases of ileus, where diarrhea is absent, specific rectal swabs may be used for diagnosis.
FAQs
What is NAAT?
NAAT is a sensitive test for detecting C. difficile toxins.
Are there other CDI tests?
Yes, enzyme immunoassays and anaerobic cultures are also used.
When should CDI testing be done?
Testing should be done for patients with unexplained diarrhea.
The Bottom Line
Understanding CDI tests can lead to quicker and more accurate diagnoses.
Additional References
- Kelly CP, Pothoulakis C, LaMont JT. Clostridium difficile colitis. N Engl J Med 1994; 330:257.
- Leffler DA, Lamont JT. Clostridium difficile infection. N Engl J Med 2015; 372:1539.
This article has been reviewed for accuracy by one of the licensed medical doctors working for Doctronic.