title: Loss of vtx genes after the first subcultivation step of verocytotoxigenic Escherichia coli O157 and Non-O157 during isolation from naturally contaminated fecal samples.
abstract: Verocytotoxins VT1 and VT2,produced by Verocytotoxigenic Escherichia coli (VTEC), are encoded on temperate bacteriophages. Several studies reported the loss of the vtx genes after multiple subcultivation steps or long preservation. The objective of this study was to determine if the loss of the verocytotoxin genes can already occur during the first subcultivation step. Consequently, the stability of the vtx genes were tested in 40 isolates originating from 40 vtx-positive fecal samples after the first subcultivation step following the isolation procedure. The loss occurred in 12 out of 40 strains tested and was rather rare among the O157 strains compared to the non-O157 strains. This is the first study demonstrating that the loss of the verocytotoxin genes can already occur after the first subcultivation step. This may lead to an underestimation of VTEC positive samples.
authors: Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, 9820 Merelbeke, Belgium. lieven.dezutter@ugent.be
authors: Maria-Adelheid
authors: MA
authors: Joris
authors: Karen
authors: K
authors: Verstraete
authors: Koen De
authors: KD
authors: Reu
authors: Lieven De
authors: LD
authors: Zutter
mesh_terms: D000818:Animals; D015373:Bacterial Typing Techniques / Q000379:methods*; D002417:Cattle; D019453:Escherichia coli O157 / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology*; D005798:Genes, Bacterial; D022622:Shiga Toxin 1 / Q000235:genetics*; D022641:Shiga Toxin 2 / Q000235:genetics*; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification
chemical_list: D022622:Shiga Toxin 1; D022641:Shiga Toxin 2