Korean J Lab Med.  2006 Dec;26(6):408-411. 10.3343/kjlm.2006.26.6.408.

Comparison of Two Enzyme Immunoassays for Clostridium difficile Toxin A

• Yoo SJ
• Kang JO
• Oh HJ
• Shin BM

• KMID: 1889818
• DOI: http://doi.org/10.3343/kjlm.2006.26.6.408

Abstract

BACKGROUND: Clostridium difficile is one of the most important pathogens responsible for nosocomial diarrhea. The disease is mediated by two toxins, designated as A and B; therefore, identification of the toxins is important for diagnosis. However, culture or cytotoxin assay are not easily done because of tedious procedures. Instead, toxin A immunoassay is widely used. We evaluated two different enzyme immunoassays (EIA) for C. difficile toxin A and compared them with culture and PCR results.
METHODS
A total of 65 stool specimens were examined for toxin A using enzyme linked fluorescent immunoassay (ELFA, VIDAS CD II, Bio-Merieux, France) and enzyme linked immunosolvent assay (ELISA, C.DIFFICILE TOX A II, TECHLAB, USA ) and were also cultured for C. difficile using cycloserine cefoxitine fructose agar. We amplified toxin A and B genes using primers NK9-NK 11 and NK104-NK105, respectively, in 23 C. difficile isolates.
RESULTS
The concordance rate between ELFA and ELISA was 76.9%. The sensitivity and specificity of the ELFA and ELISA based on the culture and PCR results for toxin A gene were 84.6%/98.1% and 84.6%/67.3%. Positive and negative predictive values were 91%/96.2% in VIDAS and 78.0%/ 94.6% in TECHLAB. The positive rates of toxin B genes were 100%, 83.3% and 50% in toxin A positive, variant and negative strains, respectively.
CONCLUSIONS
The sensitivities of the ELFA and ELISA for toxin A were the same, but specificity and positive predictive value of the ELFA were higher than those of the ELISA. PCR or EIA method detecting both toxin A and toxin B is strongly recommended, because the variant strains (toxin A negative and toxin B positive) of C. difficile may be more prevalent than were anticipated in Korea.

Keyword

Clostridium difficile; toxin A; enzyme immunoassay; PCR

MeSH Terms

Agar
Cefoxitin
Clostridium difficile*
Clostridium*
Cycloserine
Diagnosis
Diarrhea
Enzyme-Linked Immunosorbent Assay
Fructose
Genes, vif
Immunoassay
Immunoenzyme Techniques*
Korea
Polymerase Chain Reaction
Sensitivity and Specificity
Agar
Cefoxitin
Cycloserine
Fructose

Reference

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