Detection, isolation and characterization of Shiga toxin-producing Escherichia coli in retail-minced beef using PCR-based techniques, immunoassays and colony hybridization.
OBJECTIVE
To provide information on detection of Shiga toxin-producing Escherichia coli (STEC) in retail-minced beef using an approach combining (i) PCR-based techniques and automated immunoassay for stx screening and detection of the five major serogroups associated with human infection, and (ii) immunomagnetic separation (IMS) and colony hybridization assays for bacterial strain isolation.


RESULTS
Twenty-seven out of 164 minced beef samples were stx-positive by PCR-ELISA, nine of which were also positive by real-time PCR for at least one marker of the five main serogroups tested (O26, O103, O111, O145 and O157). Two E. coli O103 stx-negative strains were isolated from two out of 10 IMS and nine STEC strains that did not belong to the five main serogroups were isolated by colony hybridization.


CONCLUSIONS
PCR techniques are applicable for rapid screening of samples containing both an stx gene and an O-group marker of the five main pathogenic STEC serogroups. Isolation of STEC strains belonging to the main non-O157 serogroups remains difficult.


CONCLUSIONS
This study presents an evaluation of a multi-faceted approach for the detection of the most frequently reported human pathogenic STEC serogroups. The advantages and limits of this strategy are presented.
Auvray
F
F
Agence Française de Sécurité Sanitaire des Aliments, Laboratoire d'Etudes et de Recherches sur la Qualité des Aliments et les Procédés Agroalimentaires (AFSSA-LERQAP), Maisons-Alfort cedex, France. f.auvray@afssa.fr
Lecureuil
C
C
Taché
J
J
Leclerc
V
V
Deperrois
V
V
Lombard
B
B
D004927:Escherichia coli Infections / Q000517:prevention & control; D005838:Genotype; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D018189:Immunomagnetic Separation; D008461:Meat Products / Q000382:microbiology*; D009693:Nucleic Acid Hybridization / Q000379:methods*; D019081:O Antigens / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods*; D012703:Serotyping / Q000379:methods; D022621:Shiga Toxin / Q000235:genetics; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*
D019081:O Antigens; D022621:Shiga Toxin