Prakasan Sreepriya, Prabhakar Parmanand, Lekshmi Manjusha, Kumar Sanath, Nayak Binaya Bhusan
Department of Post-Harvest Technology, Quality Control Laboratory, ICAR-Central Institute of Fisheries Education, Versova, Mumbai, Maharashtra, India.
Vet World. 2018 Mar;11(3):379-385. doi: 10.14202/vetworld.2018.379-385. Epub 2017 Mar 28.
Shiga toxin-producing (STEC) are important pathogens of global significance. STEC are responsible for numerous food-borne outbreaks worldwide and their presence in food is a potential health hazard. The objective of the present study was to determine the incidence of STEC in fresh seafood in Mumbai, India, and to characterize STEC with respect to their virulence determinants.
A total of 368 were isolated from 39 fresh seafood samples (18 finfish and 21 shellfish) using culture-based methods. The isolates were screened by polymerase chain reaction (PCR) for the genes commonly associated with STEC. The variant Shiga toxin genes were confirmed by Southern blotting and hybridization followed by DNA sequencing.
One or more Shiga toxins genes were detected in 61 isolates. Of 39 samples analyzed, 10 (25.64%) samples harbored STEC. Other virulence genes, namely, (coding for an intimin) and (hemolysin A) were detected in 43 and 15 seafood isolates, respectively. The variant genes from 6 isolates were sequenced, five of which were found to be variants, while one sequence varied considerably from known sequences. Southern hybridization and DNA sequence analysis suggested putative Shiga toxin variant genes () in at least 3 other isolates.
The results of this study showed the occurrence of STEC in seafood harboring one or more Shiga toxin genes. The detection of STEC by PCR may be hampered due to the presence of variant genes such as the in STEC. This is the first report of gene in STEC isolated from Indian seafood.
产志贺毒素大肠杆菌（STEC）是具有全球重要意义的病原体。STEC 是全球众多食源性疾病暴发的病因，其在食品中的存在对健康构成潜在危害。本研究的目的是确定印度孟买新鲜海产品中产志贺毒素大肠杆菌（STEC）的发生率，并根据其毒力决定因素对 STEC 进行特征分析。
采用基于培养的方法，从 39 份新鲜海产品样本（18 份有鳍鱼类和 21 份贝类）中分离出总共 368 株菌株。通过聚合酶链反应（PCR）对分离株进行与 STEC 常见相关基因的筛选。通过 Southern 印迹和杂交随后进行 DNA 测序来确认变异的志贺毒素基因。
在 61 株分离株中检测到一个或多个志贺毒素基因。在分析的 39 个样本中，10 个（25.64%）样本含有 STEC。分别在 43 株和 15 株海产品分离株中检测到其他毒力基因，即编码 intimin 的 eae 和溶血素 A 的 hlyA。对 6 株分离株的变异 eae 基因进行了测序，其中 5 个被发现是 eae 变异体，而一个序列与已知的 eae 序列有很大差异。Southern 杂交和 DNA 序列分析表明至少在其他 3 株分离株中存在推定的志贺毒素变异基因（stx）。
本研究结果表明，含有一个或多个志贺毒素基因的海产品中存在 STEC。由于 STEC 中存在变异基因如 eae，通过 PCR 检测 STEC 可能会受到阻碍。这是从印度海产品中分离出的 STEC 中 eae 基因的首次报道。
