Detection of Clostridium difficile toxins A, B and binary toxin with slow off-rate modified aptamers

Diagn Microbiol Infect Dis. 2013 Jul;76(3):278-85. doi: 10.1016/j.diagmicrobio.2013.03.029. Epub 2013 May 13.


Rapid and accurate diagnostic tests for Clostridium difficile infections (CDI) are crucial for management of patients with suspected CDI and for infection control. Enzyme immunoassays for detection of the toxins are routinely used but lack adequate sensitivity. We generated slow off-rate modified aptamers (SOMAmer™ reagents) via in vitro selection (SELEX) that bind toxins A, B and binary toxin with high affinity and specificity. Using SOMAmers alone or in conjunction with antibodies, we have developed toxin assays with a 1 pmol/L (300 pg/mL) limit of detection and a 3 log dynamic range. SOMAmers proved useful as capture or detection agents in equilibrium solution binding radioassays, pull-down capture assays, dot blots, and plate- or membrane-based sandwich assays, thus represent a promising alternative to antibodies in diagnostic applications. SOMAmers detected toxins A, B and binary toxin in culture supernatants from toxigenic C. difficile, including a BI/NAP1 strain and historic strains.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aptamers, Nucleotide
  • Bacterial Proteins / analysis
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / metabolism
  • Clostridium difficile / metabolism*
  • Culture Media, Conditioned / analysis
  • Enterocolitis, Pseudomembranous / diagnosis
  • Enterocolitis, Pseudomembranous / microbiology
  • Enterotoxins / analysis
  • Enterotoxins / chemistry*
  • Enterotoxins / metabolism
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Limit of Detection
  • Peptide Fragments / chemistry
  • Protein Binding
  • SELEX Aptamer Technique


  • Aptamers, Nucleotide
  • Bacterial Proteins
  • Culture Media, Conditioned
  • Enterotoxins
  • Peptide Fragments