Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, 9820 Merelbeke, Belgium.
Toxins (Basel). 2011 Jun;3(6):672-7. doi: 10.3390/toxins3060672. Epub 2011 Jun 20.
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.
产志贺毒素的大肠埃希菌（VTEC）产生的志贺毒素 1 型（VT1）和志贺毒素 2 型（VT2）由温和噬菌体编码。多项研究报道，在多次传代培养或长期保存后，vtx 基因会丢失。本研究的目的是确定 vtx 基因的丢失是否已经发生在第一次传代培养步骤中。因此，在分离程序后进行第一次传代培养后，对来自 40 份 vtx 阳性粪便样本的 40 个分离株中的 vtx 基因的稳定性进行了测试。在 40 株测试菌株中，有 12 株发生了丢失，与非 O157 菌株相比，O157 菌株中丢失的情况较为罕见。这是首次证明 vtx 基因的丢失可能已经发生在第一次传代培养之后。这可能会导致对产志贺毒素大肠埃希菌阳性样本的低估。
