Prevalence of Stx Phages in Environments of a Pig Farm and Lysogenic Infection of the Field E. coli O157 Isolates with a Recombinant Converting Phage
Prevalence of Stx Phages in Environments of a Pig Farm and Lysogenic Infection of the Field E. coli O157 Isolates with a Recombinant Converting Phage
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养猪场环境中 Stx 噬菌体的流行以及重组转化噬菌体对田间大肠杆菌 O157 分离株的溶原性感染
DOI：
10.1007/s00284-010-9729-8
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发表时间：
2011-02-01
影响因子：
2.6
通讯作者：
Sun, Jianhe
中科院分区：
文献类型：
--
作者：
Yan, Yaxian;Shi, Yibo;Sun, Jianhe
对中国某种猪场随机采集的720份猪粪便样品进行为期1年的产滋贺毒素（Stx）大肠杆菌（STEC）和Stx噬菌体的流行病学调查。确定了8株STEC O 157（1.1%）、33株STEC非O 157（4.6%）和2株Stx阴性O 157（0.3%）分离株。用E. coliK-12衍生菌株MC 1061为指示菌，共产生15株Stx 1和57株Stx 2。诺氟沙星诱导8株STEC O 157分离株后，获得1株Stx 1和8株Stx 2菌株。所有的Stx 1 β都有六角的头部和长尾，而Stx 2 β有三种不同的形态。值得注意的是，大多数STEC O 157田间分离株在用环丙沙星诱导后释放出更多的游离β-内酰胺酶和Stx毒素。此外，在用重组噬菌体PhiMin 27（Delta stx：：cat）感染后，E.大肠杆菌实验室菌株产生溶源性和裂解性噬菌体，而八个O 157 STEC分离株中的两个仅产生溶源性噬菌体。来自实验室菌株的溶原菌产生类似于Phi Min 27的感染性颗粒。类似地，来自STEC O 157分离株的溶原菌也释放Stx噬菌体，尽管未检测到游离Phi Min 27（Delta stx：：cat）颗粒。总的来说，我们的研究结果表明，种猪场可能是重要的水库，为Stx毒素和残留的抗菌剂可能会增加释放的Stx毒素和表达。
The prevalence and nature of Shiga toxin (Stx)-producing Escherichia coli (STEC) and Stx phage were investigated in 720 swine fecal samples randomly collected from a commercial breeding pig farm in China over a 1-year surveillance period. Eight STEC O157 (1.1%), 33 STEC non-O157 (4.6%), and two stx-negative O157 (0.3%) isolates were identified. Fecal filtrates were screened directly for Stx phages using E. coli K-12 derivative strains MC1061 as indicator, yielding 15 Stx1 and 57 Stx2 phages. One Stx1 and eight Stx2 phages were obtained following norfloxacin induction of the eight field STEC O157 isolates. All Stx1 phages had hexagonal heads with long tails, while Stx2 phages had three different morphologies. Notably, most of field STEC O157 isolates released more free phages and Stx toxin after induction with ciprofloxacin. Furthermore, upon infection with the recombinant phage Phi Min27(Delta stx::cat), E. coli laboratory strains produced both lysogenic and lytic phage, whereas two of the eight O157 STEC isolates produced only lysogens. The lysogens from laboratory strains produced infectious particles similar to Phi Min27. Similarly, the lysogens from the STEC O157 isolates released Stx phage too, although free Phi Min27(Delta stx::cat) particles were not detected. Collectively, our results reveal that breeding pig farms could be important reservoirs for Stx phages and that residual antibacterial agents may enhance the release of Stx phages and the expression of Stx.