Comparison of Two Enzyme Immunoassays for Clostridium difficile Toxin A.
10.3343/kjlm.2006.26.6.408
- Author:
Soo Jin YOO
1
;
Jung Oak KANG
;
Hye Jun OH
;
Bo Moon SHIN
Author Information
1. Department of Laboratory Medicine, Sanggye Paik Hospital, Inje University, Seoul, Korea. bmshin@unitel.co.kr
- Publication Type:Original Article
- Keywords:
Clostridium difficile;
toxin A;
enzyme immunoassay;
PCR
- MeSH:
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
- From:The Korean Journal of Laboratory Medicine
2006;26(6):408-411
- CountryRepublic of Korea
- Language:Korean
-
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.
