Virulence Testing by PCR
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.
Detection of different pathogenic types of E. coli
- 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)
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
Suggested PCR screening tests for detecting virulence factors in E. coli isolates from different host
Detection of genes encoding virulence factors: toxins
- Shiga toxins 1 and 2: Stx1 and Stx2
- Heat Stable toxins a and b: STa and STb
- Heat-labile toxin: LT
- Cytotoxic Necrotizing Factors 1 and 2: CNF-1 and CNF-2
- Hemolysins: HlyA, HlyD, HlyE
Detection of genes encoding virulence factors: fimbriae/adhesins
- K88 (F4)
- K99 (F5)
- 987P (F6)
- F107 (F18)
Detection of genes encoding virulence factors for avian sp.and ExPEC
- Adhesins associated with ExPEC