Laboratory comparison between cell cytotoxicity neutralization assay and ultrasensitive single molecule counting technology for detection of Clostridioides difficile toxins A and B, PCR, enzyme immunoassays, and multistep algorithms

Diagn Microbiol Infect Dis. 2019 Sep;95(1):20-24. doi: 10.1016/j.diagmicrobio.2019.04.002. Epub 2019 Apr 9.

Abstract

Diagnostic tests for Clostridioides difficile infection (CDI) lack either specificity (nucleic acid amplification tests) or sensitivity (enzyme immunoassays; EIAs). The performance of the Singulex Clarity® C. diff toxins A/B assay was compared to cell cytotoxicity neutralization assay. Testing was also performed using an EIA for glutamate dehydrogenase (GDH) and C. difficile toxins A and B (C. Diff Quik Chek Complete®), polymerase chain reaction (PCR) (BD MAX™ Cdiff Assay), and 2 multistep algorithms: algorithm 1 (discordant GDH/toxin results arbitrated by PCR) and algorithm 2 (PCR-positive samples tested with toxin EIA). The Clarity assay and PCR both had 97% sensitivity, while specificity was 100% for Clarity and 79% for PCR. Algorithm 1 yielded 41% discordant results, and both toxin EIA and algorithm 2 had 58% sensitivity. Median toxin concentrations, as measured by the Clarity C. difficile toxin assay, were 3590, 11.5, 0.4, and 0 pg/mL for GDH+/toxin+, GDH+/toxin-/PCR+, GDH+/toxin-/PCR-, and GDH-/toxin- samples, respectively (P < 0.001). The Clarity assay may offer a single-test solution for CDI.

Keywords: C. difficile toxins; Single molecule counting technology; Ultrasensitivity.

Publication types

  • Comparative Study

MeSH terms

  • Algorithms
  • Bacterial Proteins / analysis*
  • Bacterial Toxins / analysis*
  • Bacteriological Techniques / standards*
  • Clostridioides difficile / chemistry
  • Clostridioides difficile / isolation & purification*
  • Enterocolitis, Pseudomembranous / diagnosis*
  • Enterotoxins / analysis*
  • Feces / chemistry
  • Feces / microbiology
  • Glutamate Dehydrogenase / analysis
  • Humans
  • Immunoassay / standards*
  • Polymerase Chain Reaction / standards
  • Sensitivity and Specificity

Substances

  • Bacterial Proteins
  • Bacterial Toxins
  • Enterotoxins
  • tcdA protein, Clostridium difficile
  • toxB protein, Clostridium difficile
  • Glutamate Dehydrogenase