CHAPITRE 1 - Université de Bourgogne
CHAPITRE 1 - Université de Bourgogne
CHAPITRE 1 - Université de Bourgogne
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For analysis, 800µL of enrichment broth is used to perform the VIDAS ESPT method<br />
according to the manufacturer’s instructions.<br />
The VIDAS ESPT kit inclu<strong>de</strong>s two ready-to-use components: the Solid Phase Receptacle<br />
(SPR) which is coated with specific E. coli O26, O103, O111, O145 and O157 phage<br />
proteins, and a strip which contains all the wash and release solutions.<br />
The concentration is fully automated and performed in 40 minutes using the VIDAS or mini-<br />
VIDAS instrument. The immunoconcentrated solution is then plated on specific isolation<br />
media.<br />
• Isolation media<br />
After the VIDAS ESPT protocol, 100 µL of the immunoconcentrated sample is plated on<br />
specific media: ChromID O157 (BioMérieux, Marcy l’Etoile, France) for E. coli O157<br />
isolation, Coli ID (BioMérieux, Marcy l’Etoile, France) and Bjorn Possé medium (Possé et<br />
al., 2008) for the other serogroups.<br />
• IMS<br />
After 24hours of mTSB + novobiocine enrichment, IMS using beads from Dynal®<br />
(Invitrogen Dynal AS, Oslo, Norway) coated with one type of specific antibodies against the<br />
serotype of the strain used for inoculation of the sample was performed. IMS was carried out<br />
for the five serotypes. IMS was performed according to manufacturer’s instructions. Resulting<br />
IMS solutions were plated onto selective agar media <strong>de</strong>scribed above. The performance of<br />
this manual method was compared to the automated VIDAS ESPT.<br />
RESULTS<br />
- Sensitivity and specificity study on pure culture strains<br />
The specificity study showed only two non specific bacteria with VIDAS ESPT assay. All<br />
results are <strong>de</strong>tailed in table 2.<br />
Table 2: Specificity results of VIDAS ESPT on broths of STEC and non-STEC strains.<br />
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