Proposition of an algorithm for the toxigenic C.difficile diagnosis

Abstract number: O547

Orellana M.A., Alcolea A., Barrado L., Chaves F., Babiano M.J., Rodriguez J.

Objectives: To evaluate a new test that detect C. difficile–enzyme glutamate dehydrogenase antigen (GDH) and toxin A/B in one step using the culture, like reference method; and to propose an algorithm for the routine diagnosis of CDAD.

Methods: CDAD study was performed to 970 stool samples of patients more than 1 year old, between February and October 2009. It was studied:

–Detection of GDH and Toxin A/B by ICT Techlab® C.diff Quick chek Complete (Inverness Medical)

–Culture on CLO plates (Biomerieux).

When GDH(+), toxin(-) and culture(+): direct toxin detection from culture was performed. When GDH(+), toxin(-) and culture(-): spore selection by alcohol treatment was performed and cultured on CLO plates.

Results: The 90.2% of samples were (-) to GDH, toxin and culture (875); and the 3.4% (33) (+) to those parameters. The 4.8% (47) were GDH(+), toxin(-) and culture(+), being the 48.9% (23/47) of those samples toxin(+) when direct toxin detection from culture was performed. The 1.3% (13) were GDH(+), toxin(-) and culture(-), recovering by alcohol treatment the 46.1% (6/13) of those samples, being the 15.4% (2/13) toxin(+). The 0.1% (1) was GDH(+), toxin(+) and culture(-); and the 0.1% (1) GDH(-), toxin(-) and culture(+).

The prevalence of toxigenic CD was 6.1%. The S, E, VPp and VPn of GDH compared to culture were: 98.7%, 97.9%, 81.6% and 99.8%.

The algorithm purpose is:

GDH(-)/toxin(-): not CD

GDH(+)/toxin(+): toxigenic CD

GDH(+)/toxin(-): culture. If culture(+): direct toxin from culture. If toxin(+): toxigenic CD; if (-): non toxigenic CD. If culture(-): alcohol treatment. If culture(+): toxin. If toxin(+): toxigenic CD; if (-) non toxigenic CD. If culture(-): not CD.

Conclusions: This test is reliable, sensitive and specific for detect CD from stool. The detection of direct toxin from culture allowed to recover the 48.9% of GDH(+)/toxin(-) samples, increasing the prevalence of toxigenic-CD from 3.4% to 5.8% and with alcohol treatment to 6.1%. This algorithm allows to exclude CD without additional tests when GDH is (-) (90.2% of samples). In 93.6% of samples the results can be obtain in less than 2 hours.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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