title: Growth of Stressed Strains of Four Non-O157 Shiga Toxin-Producing Escherichia coli Serogroups in Five Enrichment Broths.
abstract: The purpose of this study was to evaluate (i) the behavior of several strains of non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O103, O111, and O145) exposed to different stress conditions and (ii) the growth dynamics of stressed and nonstressed non-O157 STEC cells in five enrichment media. STEC strains were exposed to acid, cold, and freeze stresses. Lethal and sublethal injuries were determined by plating in parallel on selective and nonselective agar media. Freeze stress (8 days, 20°C) caused the most lethal (95.3% ± 2.5%) injury, as well as the most sublethal (89.1% ± 8.8%) injury in the surviving population. Growth of stressed and nonstressed pure cultures of non-O157 STEC on modified tryptic soy broth, buffered peptone water (BPW), BPW with sodium pyruvate, Brila, and STEC enrichment broth (SEB) was determined using total viable counts. To compare growth capacities, growth after 7 and 24 h of enrichment was measured; lag phases and maximum growth rates were also calculated. In general, growth on BPW resulted in a short lag phase followed by a high maximum growth rate during the enrichment of all tested strains when using all three stress types. Furthermore, BPW ensured the highest STEC count after 7 h of growth. Supplementing the medium with sodium pyruvate did not improve the growth dynamics. The two selective media, Brila and SEB, were less efficient than BPW, but Brila's enrichment performance was remarkably better than that of SEB. This study shows that irrespective of the effect of background flora, BPW is still recommended for resuscitation of non-O157 STEC.
authors.affiliation: Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium; Institute for Agricultural and Fisheries Research (ILVO), Technology and Science Food Unit, Brusselsesteenweg 370, 9090 Melle, Belgium.
authors.forename: Bavo
authors.initials: B
authors.lastname: Verhaegen
authors.affiliation: Institute for Agricultural and Fisheries Research (ILVO), Technology and Science Food 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 Science Food Unit, Brusselsesteenweg 370, 9090 Melle, Belgium. Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Heyndrickx
authors.affiliation: Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Inge
authors.initials: I
authors.lastname: Van Damme
authors.affiliation: Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. lieven.dezutter@ugent.be.
authors.forename: Lieven
authors.initials: L
authors.lastname: De Zutter
mesh_terms: D003470:Culture Media / Q000737:chemistry* / Q000378:metabolism; D065288:Serogroup; D054323:Shiga-Toxigenic Escherichia coli / Q000254:growth & development* / Q000378:metabolism
chemical_list: D003470:Culture Media