CHAPITRE 1 - Université de Bourgogne

Novel Phage Concentration Assay for Isolation of E.
coli O26, O103, O111, O145 and O157
F.SAVOYE a , M. BOUVIER a , J-L. PITTET b , D. THEVENOT-SERGENTET a
a VetAgro Sup Campus vétérinaire de Lyon, Unité de Microbiologie alimentaire et
Prévisionnelle, 1 avenue Bourgelat, 69280, Marcy l’Etoile. France
Tel : 3347882685, Fax: 33478872669, email : f.savoye@vetagro-sup.fr
b BioMérieux, R&D Industrie, chemin de l’orme, 69280, Marcy l’Etoile. France
ABSTRACT
Shiga toxin-producing Escherichia coli (STEC) that cause hemorrhagic diarrhoeal disease and
Haemolytic and Uremic Syndrome are associated with some predominant serotypes: O26,
O103, O111, O145 and O157. This study was designed to develop and optimize an automated
immuno-concentration of E. coli O157, O26, O103, O111 and O145 with the use of specific
recombinant phage proteins for capture. Immuno-concentration specificity was evaluated with
50 pure culture strains (E. coli O157, O26, O103, O111, O145, STEC and non-STEC).
Sensitivity of the method was determined using meat products enriched in buffered peptone
water (BPW) and experimentally inoculated with low number of STEC (10 1 to 10 7 CFU/ml)
just prior to applying the immuno-concentration method. The method was then evaluated on
food samples artificially contaminated with stressed cells and enriched in BPW for 24 hours
at 41.5°C. The inclusivity and exclusivity study clearly showed that the method was highly
specific for the targeted strains. The immuno-concentration was shown to be sensitive enough
for isolation of very low levels of cold-adapted strains (1 to 5 CFU/25g) in artificially
contaminated foods after enrichment.
INTRODUCTION
STEC that cause hemorrhagic diarrhoeal disease and Haemolytic and Uremic Syndrome are
associated with some predominant serogroups such as O157, O26, O103, O111 and O145.
These serogroups have been referred to as “the gang of five” (Beutin, 2006). Their high
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