Trung Nguyen Vinh, Nhung Hoang Ngoc, Carrique-Mas Juan J, Mai Ho Huynh, Tuyen Ha Thanh, Campbell James, Nhung Nguyen Thi, Van Minh Pham, Wagenaar Jaap A, Mai Nguyen Thi Nhu, Hieu Thai Quoc, Schultsz Constance, Hoa Ngo Thi
Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Department of Global Health-Amsterdam Institute for Global Health and Development, Amsterdam, The Netherlands.
BMC Microbiol. 2016 Sep 9;16(1):208. doi: 10.1186/s12866-016-0827-z.
Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E. coli O104:H4 in Europe in 2011. We assessed the opportunities for E. coli carrying the aggR and stx genes to emerge in 'backyard' farms in south-east Asia.
Faecal samples collected from 204 chicken farms; 204 farmers and 306 age- and gender-matched individuals not exposed to poultry farming were plated on MacConkey agar plates with and without antimicrobials being supplemented. Sweep samples obtained from MacConkey agar plates without supplemented antimicrobials were screened by multiplex PCR for the detection of the stx1, stx2 and aggR genes. One chicken farm sample each (0.5 %) contained the stx1 and the aggR gene. Eleven (2.4 %) human faecal samples contained the stx1 gene, 2 samples (0.4 %) contained stx2 gene, and 31 (6.8 %) contained the aggR gene. From 46 PCR-positive samples, 205 E. coli isolates were tested for the presence of stx1, stx2, aggR, wzx O104 and fliC H4 genes. None of the isolates simultaneously contained the four genetic markers associated with E. coli O104:H4 epidemic strain (aggR, stx2, wzx O104 and fliC H4 ). Of 34 EAEC, 64.7 % were resistant to 3(rd)-generation cephalosporins.
These results indicate that in southern Vietnam, the human population is a more likely reservoir of aggR and stx gene carrying E. coli than the chicken population. However, conditions for transmission of isolates and/or genes between human and animal reservoirs resulting in the emergence of highly virulent E. coli strains are still favorable, given the nature of'backyard' farms in Vietnam.
肠集聚性（EAEC）和产志贺毒素大肠杆菌（STEC）是全球腹泻的主要病因。2011年欧洲大肠杆菌O104:H4疫情期间，携带EAEC和STEC特征性毒力因子并产生超广谱β-内酰胺酶的大肠杆菌引发了严重且迁延不愈的疾病。我们评估了东南亚“后院”农场中携带aggR和stx基因的大肠杆菌出现的可能性。
从204个养鸡场采集粪便样本；将204名农民以及306名年龄和性别匹配且未接触家禽养殖的个体的粪便样本接种在添加和未添加抗菌药物的麦康凯琼脂平板上。对未添加抗菌药物的麦康凯琼脂平板上获得的横扫样本进行多重PCR筛选，以检测stx1、stx2和aggR基因。各有一个养鸡场样本（0.5%）含有stx1和aggR基因。11份（2.4%）人类粪便样本含有stx1基因，2份（0.4%）含有stx2基因，31份（6.8%）含有aggR基因。对46份PCR阳性样本中的205株大肠杆菌分离株检测stx1、stx2、aggR、wzx O104和fliC H4基因的存在情况。没有分离株同时含有与大肠杆菌O104:H4流行菌株相关的四个遗传标记（aggR、stx2、wzx O104和fliC H4）。在34株EAEC中，64.7%对第三代头孢菌素耐药。
这些结果表明，在越南南部，人类群体比鸡群更有可能是携带aggR和stx基因的大肠杆菌的宿主。然而，鉴于越南“后院”农场的性质，分离株和/或基因在人类和动物宿主之间传播从而导致高毒力大肠杆菌菌株出现的条件仍然有利。
