CHAPITRE 1 - Université de Bourgogne
CHAPITRE 1 - Université de Bourgogne
CHAPITRE 1 - Université de Bourgogne
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IMS sensitivity may also be affected by the bead-to-organism ratio used the enrichment broth,<br />
and the problem of non-specific adsorption to the magnetic beads (which can be reduced by<br />
the use of a low ionic strength solution in the IMS procedure and washing).Other studies have<br />
evaluated the efficiency of IMS: the O26 and O111 IMS beads have been evaluated for the<br />
<strong>de</strong>tection of these STEC serogroups in vegetables (Safarikova and Safarik, 2001) and O103<br />
IMS beads have been used to <strong>de</strong>tect O103 serogroup in sheep faecal samples (Urdahl et al.,<br />
2002). Safarikova and Safarik (2001) found that IMS increased the isolation of E. coli O26,<br />
O103 and O111 in vegetables with 93-100% of samples positive by IMS compared to 36-93%<br />
using direct culture.<br />
Our study showed that the VIDAS ESPT can perform the immuno-concentration<br />
automatically within 60 min for the five serogroups reported, with a maximum capacity of 30<br />
samples in one run. In contrast, for the IMS method the concentration of 30 samples for one<br />
serogroup takes about 100 min when using two magnetic particle concentrators, each fitted to<br />
handle 6 samples at a time (Aminul Islam et al., 2006). Aminul Islam et al. (2006) found that<br />
IMS method also has a potential risk for cross-contamination during the performance of<br />
immunomagnetic separation. Compared with IMS method, the VIDAS ESPT are less time-<br />
consuming and are fully automated and thus less labor intensive.<br />
This study has <strong>de</strong>monstrated that the VIDAS ESPT is a promising tool to isolate E. coli O157,<br />
O26, O103, O111 and O145 from food in a single assay, facilitates their subsequent<br />
i<strong>de</strong>ntification on selective agar plates.<br />
This test could be used as a sample preparation in or<strong>de</strong>r to establish pathogenic status of<br />
enrichment broth with a PCR assay. It would reduced the number of non-relevant PCR<br />
positive results and so the number of confirmation. This automated method will provi<strong>de</strong><br />
technical and economic advantages to the food industry for routine testing by reducing the<br />
number of false positive PCR screen samples that need to be run through the confirmation<br />
process. Works are un<strong>de</strong>rway in or<strong>de</strong>r to validate these data.<br />
REFERENCES<br />
Aminul Islam, M., A. E. Heuvelink, K. A. Taluk<strong>de</strong>r, and E. <strong>de</strong> Boer. 2006.<br />
Immunoconcentration of Shiga toxin–producing Escherichia coli O157 from animal faeces<br />
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