Department of Microbiology, Hazara University, Garden Campus, Mansehra, 21300, Pakistan.
Animal Health Program, Animal Sciences Institute, National Agricultural Research Centre (NARC), Park Road, Islamabad, 44000, Pakistan.
Mol Biol Rep. 2021 Aug;48(8):6113-6121. doi: 10.1007/s11033-021-06631-3. Epub 2021 Aug 10.
Shiga toxin-producing E. coli (STEC) are important foodborne pathogens that causing serious public health consequences worldwide. The present study aimed to estimate the prevalence ratio and to identify the zoonotic potential of E. coli O157 isolates in slaughtered adult sheep, goats, cows and buffaloes.
A total of 400 Recto-anal samples were collected from two targeted sites Rawalpindi and Islamabad. Among them, 200 samples were collected from the slaughterhouse of Rawalpindi included sheep (n = 75) and goats (n = 125). While, 200 samples were collected from the slaughterhouse of Islamabad included cows (n = 120) and buffalos (n = 80). All samples were initially processed in buffered peptone water and then amplified by conventional PCR. Samples positive for E. coli O157 were then streaked onto SMAC media plates. From each positive sample, six different Sorbitol fermented pink-colored colonies were isolated and analyzed again via conventional PCR to confirm the presence of rfbE O157 gene. Isolates positive for rfbE O157 gene were then further analyzed by multiplex PCR for the presence of STEC other virulent genes (sxt1, stx2, eae and ehlyA) simultaneously.
Of 400 RAJ samples only 2 (0.5%) showed positive results for E. coli O157 gene, included sheep 1/75 (1.33%) and buffalo 1/80 (1.25%). However, goats (n = 125) and cows (n = 120) found negative for E. coli O157. Only 2 isolates from each positive sample of sheep (1/6) and buffalo (1/6) harbored rfbE O157 genes, while five isolates could not. The rfbE O157 isolate (01) of sheep sample did not carry any of STEC genes, while the rfbE O157 isolate (01) of buffalo sample carried sxt1, stx2, eae and ehlyA genes simultaneously.
It was concluded that healthy adult sheep and buffalo are possibly essential carriers of STEC O157. However, rfbE O157 isolate of buffalo RAJ sample carried 4 STEC virulent genes, hence considered an important source of STEC infection to humans and environment which should need to devise proper control systems.
产志贺毒素大肠杆菌（STEC）是重要的食源性病原体，在全球范围内造成严重的公共卫生后果。本研究旨在估计屠宰成年绵羊、山羊、牛和水牛中大肠杆菌 O157 分离株的流行率比值，并确定其人畜共患病潜力。
从拉瓦尔品第和伊斯兰堡两个目标地点采集了 400 份直肠-肛门样本。其中，200 份样本来自拉瓦尔品第屠宰场，包括绵羊（n=75）和山羊（n=125）。而 200 份样本来自伊斯兰堡屠宰场，包括牛（n=120）和水牛（n=80）。所有样本最初均在缓冲蛋白胨水中进行处理，然后通过常规 PCR 进行扩增。对大肠杆菌 O157 呈阳性的样本随后在 SMAC 培养基平板上划线。从每个阳性样本中分离出 6 个不同的山梨糖醇发酵粉红色菌落，并再次通过常规 PCR 分析以确认 rfbE O157 基因的存在。对 rfbE O157 基因呈阳性的分离株进一步通过多重 PCR 同时分析 STEC 其他毒力基因（sxt1、stx2、eae 和 ehlyA）的存在情况。
在 400 份 RAJ 样本中，只有 2 份（0.5%）显示出大肠杆菌 O157 基因阳性，包括绵羊 1/75（1.33%）和水牛 1/80（1.25%）。然而，山羊（n=125）和牛（n=120）均呈大肠杆菌 O157 阴性。只有绵羊（1/6）和水牛（1/6）的每个阳性样本中的 2 个分离株携带 rfbE O157 基因，而其他 5 个分离株未携带。绵羊样本 rfbE O157 分离株（01）未携带任何 STEC 基因，而水牛样本 rfbE O157 分离株（01）同时携带 sxt1、stx2、eae 和 ehlyA 基因。
健康的成年绵羊和水牛可能是 STEC O157 的重要携带者。然而，水牛 RAJ 样本的 rfbE O157 分离株携带 4 种 STEC 毒力基因，因此被认为是人类和环境中 STEC 感染的重要来源，需要制定适当的控制系统。
