Table 4.

—Clostridium difficile Diagnostic Tests: Advantages and Limitations

Test	Advantages	Limitations	Other
GDH EIAa	Triage tool if for screening, inexpensive	Need confirmatory test, sensitivity varies	Nontoxigenic also positive
Toxin A/B EIAb	Inexpensive, rapid, relatively little expertise	Wide variation in sensitivity and specificity	Toxin A negative strains exist, so use A/B EIA
Toxin B PCR	Several hours, relatively little expertise	Expensive, not validated, may be overly sensitive	Occasional toxin B PCR positive but strain not cytotoxicc
Direct stool cytotoxicityd	High specificity	48-96 h, tissue culture facility, low sensitivity, expensive, technical expertise
Cytotoxigenic culturee	Gold standard, epidemiologic studies of strain type	48-96 h, anaerobic and tissue culture facility, expensive, technical expertise	Could be mixture of toxin positive and negative strains

EIA = enzyme immunoassay; GDH = glutamate dehydrogenase; PCR = polymerase chain reaction.

^aGDH followed by a more sensitive test, such as PCR or cytotoxicity.

^bEIA must include A and B.

^cL. Bobo, MD, PhD, unpublished data.

^dTissue culture of stool.

^eAnaerobic culture of stool followed by tissue culture on isolate.