CHAPITRE 1 - Université de Bourgogne

Strains
Number
tested
Detected after
VIDAS ESPT
E. coli O26 10 10
E. coli O103 10 10
E. coli O111 4 4
E. coli O145 7 7
E. coli O157 10 10
Others (Citrobacter, E.
coli, Staphylococcus …)
11 2
The sensitivity study performed on the dilutions of pure cultures of STEC showed a threshold
of the VIDAS ESPT around 10 2 -10 3 CFU/mL. The same study made with dilutions of specific
STEC strains mixed with non-specific bacteria, showed a sensitivity threshold of the test
between 10 2 and 10 4 CFU/mL according to serogroups (Table 3).
Table 3: Threshold concentration for VIDAS ESPT on broths of STEC and non-STEC strains.
Serogroup O26 O103 O111 O145 O157
ESPT sensitivity (CFU/mL) pure
broth suspension of STEC
ESPT sensitivity (CFU/mL) broth
suspension of STEC with another
non-STEC bacteria
10 3 10 2 10 2 10 3 10 2
10 4 10 2 10 2 10 4 10 2
The threshold was determined as soon as specific strains were isolated on plates
- Sensitivity study on artificially inoculated samples
The assay performed post-enrichment, on artificially inoculated samples showed a sensitivity
threshold of the VIDAS ESPT for E. coli O26, O103, O111, O145 and O157 research around
10 3 -10 4 CFU/mL according to the serogroups. With the IMS method the results showed a
sensitivity threshold of 10 3 -10 5 CFU/mL according to the serogroups (Table 4).
Table 4: Performance of two immuno-concentration methods: VIDAS ESPT and IMS, for the
isolation of “gang of five” in post enriched raw ground beef samples artificially inoculated.
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