Diagnosis
➤ Before testing a NICU patient with suspected infectious diarrhea for
CDI, clinicians should:
• Perform a thorough investigation for potential noninfectious causes of
diarrhea in NICU patients.
• Test the stool for norovirus, rotavirus, adenovirus, and enterovirus.
• Consider bacterial stool cultures (e.g., Salmonella, Shigella, Campylobacter,
Yersinia, and Shiga-toxin–producing E. coli) for infants who were admitted to
the NICU from the community, or who have a known or suspected exposure
to bacterial enteritis.
• If clinicians consider testing a NICU patient for CDI, the authors advise
using a stool toxin test as part of a multistep algorithm rather than using a
nucleic acid amplification test (NAAT) alone.
• The facility should not use toxin enzyme immunoassay (EIA) as a stand-alone
test to diagnose CDI.
• Repeat testing after a negative result and tests of cure are not recommended.
➤ Because CDI is a toxin-mediated disease, any testing strategy must
include detection of either toxin or a toxigenic organism.
1. NAATs, primarily polymerase chain reaction testing for the genes for toxins
A and B,
▶ are more sensitive for C. difficile detection than toxin EIA tests, but
▶ their positive predictive value can be low, particularly when the prevalence
of colonization is high (as is true for infants).
2. Toxin EIA testing :
▶ in addition to having lower sensitivity than NAAT, may also be prone to
false-positive results in children.
▶ is not recommended as a stand-alone approach to diagnosis.
3. Glutamate dehydrogenase (GDH) immunoassays:
▶ detect a highly conserved antigen present in all C. difficile isolates.
▶ can be used as a component of 2- or 3-step algorithms with subsequent
toxin testing, in which a negative toxin EIA result is sometimes arbitrated
by NAAT as outlined in the IDSA/SHEA guideline.
