title: Comparison of Six Chromogenic Agar Media for the Isolation of a Broad Variety of Non-O157 Shigatoxin-Producing Escherichia coli (STEC) Serogroups.
abstract: The isolation of non-O157 STEC from food samples has proved to be challenging. The selection of a suitable selective isolation agar remains problematic. The purpose of this study was to qualitatively and quantitatively evaluate six chromogenic agar media for the isolation of STEC: Tryptone Bile X-glucuronide agar (TBX), Rainbow® Agar O157 (RB), Rapid E. coli O157:H7 (RE), Modified MacConkey Agar (mMac), CHROMagarTM STEC (Chr ST) and chromIDTM EHEC (Chr ID). During this study, 45 E. coli strains were used, including 39 STEC strains belonging to 16 different O serogroups and 6 non-STEC E. coli. All E. coli strains were able to grow on TBX and RB, whereas one STEC strain was unable to grow on Chr ID and a number of other STEC strains did not grow on mMac, CHROMagar STEC and Rapid E. coli O157:H7. However, only the latter three agars were selective enough to completely inhibit the growth of the non-STEC E. coli. Our conclusion was that paired use of a more selective agar such as CHROMagar STEC together with a less selective agar like TBX or Chr ID might be the best solution for isolating non-O157 STEC from food.
authors.affiliation: Institute for Agricultural and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, 9090 Melle, Belgium. lieven.dezutter@ugent.be.|Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. lieven.dezutter@ugent.be.
authors.forename: Bavo
authors.initials: B
authors.lastname: Verhaegen
authors.affiliation: Institute for Agricultural and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, 9090 Melle, Belgium. Koen.DeReu@ilvo.vlaanderen.be.
authors.forename: Koen
authors.initials: K
authors.lastname: De Reu
authors.affiliation: Institute for Agricultural and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, 9090 Melle, Belgium. Marc.Heyndrickx@ilvo.vlaanderen.be.|Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. Marc.Heyndrickx@ilvo.vlaanderen.be.
authors.forename: Marc
authors.initials: M
authors.lastname: Heyndrickx
authors.affiliation: Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. lieven.dezutter@ugent.be.
authors.forename: Lieven
authors.initials: L
authors.lastname: De Zutter
mesh_terms: D000362:Agar; D003470:Culture Media / Q000592:standards*; D004927:Escherichia coli Infections / Q000453:epidemiology*; D006801:Humans; D065288:Serogroup; D054323:Shiga-Toxigenic Escherichia coli / Q000302:isolation & purification
chemical_list: D003470:Culture Media; D000362:Agar
keywords: agar media; chromogenic; isolation; non-O157; quantitative; shigatoxin-producing E. coli