Information on Services
SEROTYPING
O serotyping is performed following the procedure published by Orskov et al. 1977. Serology, Chemistry, and genetics of O and K antigens of Escherichia coli. Bacteriol. Rev. 41:667-710. The standard strains used are those described in the paper.
H typing is performed by the method described by Machado et al. 2000. Identification of Escherichia coli flagellar types by restriction of the amplified fliC gene. Res. Microbiol. 151:535-546
Virulent 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 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 urinary tract infection (UTI) in humans and animals
- CNF2: associated with UTI in humans and animals
Detection of fimbriae and adhesin genes associated with E. coli
The presence of the following adhesin/fimbriae genes are determined by PCR technique.
- 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 ETEC 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 diarrheal diseases
Suggested PCR screening tests for detecting virulence factors in E. coli isolates from different host
| Host | LT | STa | STb | Stx1 | Stx2 | CNF1 | CNF2 | EAE | K88 | K99 |
|---|---|---|---|---|---|---|---|---|---|---|
| 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 | |||||
| Host | 987P | F107 | CS31A | F1845 | BFP | iss | tsh | K1 | hlyE | |
| Bovine | X | X | ||||||||
| Porcine | X | X | ||||||||
| Equine | ||||||||||
| Canine | ||||||||||
| Feline | ||||||||||
| Human | X | |||||||||
| Avian | X | X | X | X | X | |||||
Special Services
Screening petting zoo animals for the presence of E. coli O157 and STEC: The procedure has been described in the following publication ( DebRoy C. and Roberts E. 2006. Screening petting zoo animals for the presence of potentially pathogenic Escherichia coli. J. Vet. Diag. Invest.18: 597-600)
Monitoring fruits and vegetables for all pathogenic E. coli strains, EPEC, ETEC, EHEC, STEC, EAEC, EIEC and NTEC are conducted by standard procedures as developed by the Microbiological Data Program (MDP) of USDA.
ERIC-PCR is performed by the methods described by Meacham KJ et al. 2003 Evaluation of genotyping large numbers of Escherichia coli isolates by enterobacterial repetitive intergenic consensus PCR, J. Clin. Microbiol. 41: 5224-5226.
PFGE is performed by the method described by Gautom RK.1997. Rapid pulsed-field gel electrophoresis protocol for typing of Escherichia coli O157:H7 and other gram-negative organisms in 1 day. J Clin Microbiol. 35 :2977-80.