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Year : 2011  |  Volume : 29  |  Issue : 3  |  Page : 293--296

Comparison between the two-step and the three-step algorithms for the detection of toxigenic Clostridium difficile

MO Qutub, N AlBaz, P Hawken, A Anoos 
 Departments Pathology and Laboratory Medicine, Medical Technologist, MBC: J-10, King Faisal Specialist Hospital and Research Centre, Jeddah-Branch, P.O. Box 40047, Jeddah 21499, Saudi Arabia

Correspondence Address:
M O Qutub
Departments Pathology and Laboratory Medicine, Medical Technologist, MBC: J-10, King Faisal Specialist Hospital and Research Centre, Jeddah-Branch, P.O. Box 40047, Jeddah 21499
Saudi Arabia

Purpose: To evaluate usefulness of applying either the two-step algorithm (Ag-EIAs and CCNA) or the three-step algorithm (all three assays) for better confirmation of toxigenic Clostridium difficile. The antigen enzyme immunoassays (Ag-EIAs) can accurately identify the glutamate dehydrogenase antigen of toxigenic and nontoxigenic Clostridium difficile. Therefore, it is used in combination with a toxin-detecting assay [cell line culture neutralization assay (CCNA), or the enzyme immunoassays for toxins A and B (TOX-A/BII EIA)] to provide specific evidence of Clostridium difficile-associated diarrhoea. Materials and Methods: A total of 151 nonformed stool specimens were tested by Ag-EIAs, TOX-A/BII EIA, and CCNA. All tests were performed according to the manufacturer«SQ»s instructions and the results of Ag-EIAs and TOX-A/BII EIA were read using a spectrophotometer at a wavelength of 450 nm. Results: A total of 61 (40.7%), 38 (25.3%), and 52 (34.7%) specimens tested positive with Ag-EIA, TOX-A/BII EIA, and CCNA, respectively. Overall, the sensitivity, specificity, negative predictive value, and positive predictive value for Ag-EIA were 94%, 87%, 96.6%, and 80.3%, respectively. Whereas for TOX-A/BII EIA, the sensitivity, specificity, negative predictive value, and positive predictive value were 73.1%, 100%, 87.5%, and 100%, respectively. With the two-step algorithm, all 61 Ag-EIAs-positive cases required 2 days for confirmation. With the three-step algorithm, 37 (60.7%) cases were reported immediately, and the remaining 24 (39.3%) required further testing by CCNA. By applying the two-step algorithm, the workload and cost could be reduced by 28.2% compared with the three-step algorithm. Conclusions: The two-step algorithm is the most practical for accurately detecting toxigenic Clostridium difficile, but it is time-consuming.

How to cite this article:
Qutub M O, AlBaz N, Hawken P, Anoos A. Comparison between the two-step and the three-step algorithms for the detection of toxigenic Clostridium difficile.Indian J Med Microbiol 2011;29:293-296

How to cite this URL:
Qutub M O, AlBaz N, Hawken P, Anoos A. Comparison between the two-step and the three-step algorithms for the detection of toxigenic Clostridium difficile. Indian J Med Microbiol [serial online] 2011 [cited 2019 Dec 8 ];29:293-296
Available from: http://www.ijmm.org/article.asp?issn=0255-0857;year=2011;volume=29;issue=3;spage=293;epage=296;aulast=Qutub;type=0