Deletions in the Repeating Sequences of the Toxin A Gene of Toxin A-negative, Toxin B-positive Clostridium Difficile Strains

FEMS Microbiol Lett. 1999 Jun 15;175(2):197-203. doi: 10.1111/j.1574-6968.1999.tb13620.x.


The repeating sequences of the toxin A gene from toxin A-negative, toxin B-positive (toxin A-, toxin B+) strains of Clostridium difficile which were isolated in geographically separated facilities in Japan and Indonesia were determined. All six strains tested had identical repeating sequences with two deletions (1548 and 273 nucleotides in size) in the toxin A gene. A PCR method was designed to detect the deletions and the deletions were confirmed in all 50 toxin A-, toxin B+ strains examined by this method. Western immunoblot analysis revealed that polyclonal antiserum against native toxin A did not react with the concentrated culture filtrates of the toxin A-, toxin B+ strains. These results may suggest that toxin A-, toxin B+ strains have deletions of the two thirds of the repeating regions of the toxin A gene, which encodes the epitopes fully responsible for the reaction with the polyclonal antiserum.

MeSH terms

  • Adult
  • Amino Acid Sequence
  • Bacterial Proteins*
  • Bacterial Toxins / metabolism*
  • Child
  • Clostridium difficile / genetics*
  • Clostridium difficile / metabolism
  • Electrophoresis, Polyacrylamide Gel
  • Enterocolitis, Pseudomembranous / microbiology*
  • Enterotoxins / genetics*
  • Genes, Bacterial
  • Humans
  • Immunoblotting
  • Molecular Sequence Data
  • Reverse Transcriptase Polymerase Chain Reaction / methods
  • Sequence Analysis, DNA
  • Sequence Deletion*
  • Transcription, Genetic


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

Associated data

  • GENBANK/AB012304