Virulence Testing by PCR

We have validated PCR reactions for identifying over three dozen genes associated with pathogenic and non-pathogenic isolates. The most common requests are detailed below, but please feel free to contact us if your specific need is not listed.

Presence of genes encoding for different virulence factors are tested by PCR using the protocols published in the following paper.

DebRoy, C. and Maddox, C. 2001. Assessing virulence of Escherichia coli isolates of veterinary significance. Animal Health Research Reviews 1: 129-140.

We have toxin and fimbriae gene panels for detecting specific pathotypes of E. coli, and for the most common host-associated virulence factors.

We have PCR panels for detecting the following pathotypes:

  • Enterohemorrhagic E. coli (EHEC) or Shiga-toxin producing E. coli (STEC)
  • Enteropathogenic E. coli (EPEC)
  • Enterotoxigenic E. coli (ETEC)
  • Enteroinvasive E. coli (EIEC)
  • Enteroaggregative E. coli (EAEC)
  • Necrotoxigenic E. coli (NTEC)
  • Extraintestinal Pathogenic E. coli (ExPEC)

Suggested PCR screening tests for detecting virulence factors in E. coli isolates from different host

Bovine   X   X X X X X   X
Porcine X X X X X X X X X X
Equine X X X X X X X X    
Canine X X X X X X X X    
Feline X X X X X X X X    
Human X X X X X X X X    
Avian       X X X X X    


Bovine     X X            
Porcine X X  
Human X  
Avian X X X X X X

Detection of Toxins associated with E. coli

  • STa: Associated with cultures from bovine
  • STb: Mostly associated with cultures from porcine
  • LT: Mostly associated with cultures from porcine
  • Stx1: Associated with EHEC and STEC strains
  • Stx2: Associated with EHEC and STEC strains
  • CNF1: Associated with  pathogenic strains
  • CNF2: Associated with pathogenic strains

Detection of fimbriae and adhesin genes associated with E. coli

  • F4 (K88): commonly associated with ETEC isolates from porcine.
  • F5 (K99): associated with ETEC strains from porcine, bovine, and sheep.
  • F6 (987P): associated with strains from porcine.
  • F41: associated with  strains isolated from porcine, bovine, and sheep.
  • F18 (F107): associated with strains from porcine edema disease and postweaning diarrhea.
  • F1845: associated with strains from bovine.
  • CS31A: associated with septicemic and enterotoxigenic strains found in bovine and recently isolated from diarrheagenic strains from humans.
  • Eae (intimin): associated with EHEC and EPEC strains.
  • BFP: bundle forming pilus associated with E. coli causing diarrheal diseases