Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Changping, Beijing, China.
PLoS One. 2013 Jun 11;8(6):e65537. doi: 10.1371/journal.pone.0065537. Print 2013.
Shiga toxin (Stx)-producing Escherichia coli (STEC) are recognized as important human pathogens of public health concern. Many animals are the sources of STEC. In this study we determined the occurrence and characteristics of the STEC in yaks (Bos grunniens) from the Qinghai-Tibetan plateau, China. A total of 728 yak fecal samples was collected from June to August, 2012 and was screened for the presence of the stx 1 and stx 2 genes by TaqMan real-time PCR after the sample was enriched in modified Tryptone Soya Broth. Of the 138 (18.96%) stx 1 and/or stx 2-positive samples, 85 (61.59%) were confirmed to have at least 1 STEC isolate present by culture isolation, from which 128 STEC isolates were recovered. All STEC isolates were serotyped, genotyped by pulsed-field gel electrophoresis (PFGE) and characterized for the presence of 16 known virulence factors. Fifteen different O serogroups and 36 different O:H serotypes were identified in the 128 STEC isolates with 21 and 4 untypable for the O and H antigens respectively. One stx 1 subtype (stx 1a) and 5 stx 2 subtypes (stx 2a, stx 2b, stx 2c, stx 2d and stx 2g) were present in these STEC isolates. Apart from lpfA O157/OI-141, lpfA O157/OI-154, lpfA O113, katP and toxB which were all absent, other virulence factors screened (eaeA, iha, efa1, saa, paa, cnf1, cnf2, astA, subA, exhA and espP) were variably present in the 128 STEC isolates. PFGE were successful for all except 5 isolates and separated them into 67 different PFGE patterns. For the 18 serotypes with 2 or more isolates, isolates of the same serotypes had the same or closely related PFGE patterns, demonstrating clonality of these serotypes. This study was the first report on occurrence and characteristics of STEC isolated from yaks (Bos grunniens) from the Qinghai-Tibetan plateau, China, and extended the genetic diversity and reservoir host range of STEC.
产志贺毒素大肠杆菌（STEC）被认为是重要的公共卫生关注的人类病原体。许多动物是 STEC 的来源。在这项研究中，我们确定了来自中国青藏高原的牦牛（Bos grunniens）中 STEC 的发生和特征。2012 年 6 月至 8 月期间，共采集了 728 份牦牛粪便样本，在改良的 Tryptone Soya Broth 中富集后，通过 TaqMan 实时 PCR 检测stx 1 和 stx 2 基因的存在。在 138 份（18.96%）stx 1 和/或 stx 2 阳性样本中，通过培养分离证实了 85 份（61.59%）至少存在 1 株 STEC 分离株，从中回收了 128 株 STEC 分离株。所有 STEC 分离株均进行了血清型鉴定，通过脉冲场凝胶电泳（PFGE）进行了基因型鉴定，并对 16 种已知毒力因子的存在情况进行了特征分析。在 128 株 STEC 分离株中，鉴定出 15 个不同的 O 血清群和 36 个不同的 O:H 血清型，其中 21 个 O 抗原和 4 个 H 抗原无法定型。这些 STEC 分离株中存在 1 种 stx 1 亚型（stx 1a）和 5 种 stx 2 亚型（stx 2a、stx 2b、stx 2c、stx 2d 和 stx 2g）。除了 lpfA O157/OI-141、lpfA O157/OI-154、lpfA O113、katP 和 toxB 均不存在外，筛选出的其他毒力因子（eaeA、iha、efa1、saa、paa、cnf1、cnf2、astA、subA、exhA 和 espP）在 128 株 STEC 分离株中呈不同程度存在。除 5 株分离株外，所有分离株均成功进行了 PFGE，共分离出 67 种不同的 PFGE 模式。对于有 2 个或更多分离株的 18 个血清型，相同血清型的分离株具有相同或密切相关的 PFGE 模式，表明这些血清型具有克隆性。本研究首次报道了来自中国青藏高原的牦牛（Bos grunniens）中 STEC 的发生和特征，扩展了 STEC 的遗传多样性和储存宿主范围。
