Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
Quantitative Veterinary Epidemiology Group, Wageningen Institute of Animal Sciences (WIAS), Wageningen University, Wageningen, The Netherlands.
J Antimicrob Chemother. 2018 Dec 1;73(12):3298-3304. doi: 10.1093/jac/dky362.
To determine the molecular characteristics of ESBL-producing Escherichia coli (ESBL-E) collected during a longitudinal study on an organic broiler farm in order to investigate clonal expansion and horizontal gene transfer.
Isolates were obtained from a longitudinal study performed previously on an organic broiler fattening farm. Samples from individually followed-up broilers, the broiler house, the transport van and persons that took the samples, taken at several timepoints (days 1, 3, 4, 7, 10, 42 and 70) within a production round and during the consecutive one (days 1, 2, 3 and 70), had been investigated for the occurrence of ESBL-E. In the current study, ESBL genes and MLST STs of these ESBL-E were determined. Plasmids were characterized and subtyped.
On arrival in round_1, ESBL-E of ST88 predominated, while on days 3, 4, 7 and 10 ST10 was most often found and at slaughter age ST155 and ST1551 prevailed. A shift in STs was also observed in round_2. None of the 35 individually selected broilers followed up in round_1 was positive for the same ESBL-E ST at all sampling times. All isolates carried CTX-M-1 group genes, confirmed as blaCTX-M-1 in 158 isolates. Further analysis of 36 isolates of different STs showed blaCTX-M-1 on IncI1/ST3 plasmids.
The rapid dissemination of ESBL-E on this broiler farm was not due to the spread of one specific E. coli clone, but most likely the result of horizontal transfer of an IncI1/ST3 plasmid carrying blaCTX-M-1 resulting in a shift in the predominant ESBL-E population in broilers.
为了研究克隆扩张和水平基因转移，对有机肉鸡养殖场进行的纵向研究中收集的产超广谱β-内酰胺酶（ESBL）大肠杆菌（ESBL-E）的分子特征进行确定。
从先前在有机肉鸡育肥场进行的纵向研究中获得分离株。对在一个生产周期内的几个时间点（第 1、3、4、7、10、42 和 70 天）以及在连续的生产周期内（第 1、2、3 和 70 天）从单独跟踪的肉鸡、鸡舍、运输货车和取样人员中采集的样本进行了 ESBL-E 的发生情况调查。在本研究中，确定了这些 ESBL-E 的 ESBL 基因和 MLST ST。对质粒进行了特征和亚型分析。
在第 1 轮到达时，ST88 型 ESBL-E 占主导地位，而在第 3、4、7 和 10 天，ST10 最常见，在屠宰年龄时 ST155 和 ST1551 占主导地位。在第 2 轮也观察到了 ST 的变化。在第 1 轮中，35 只单独选择的肉鸡中，没有一只在所有采样时间都对相同的 ESBL-E ST 呈阳性。所有分离株均携带 CTX-M-1 组基因，在 158 株分离株中证实为 blaCTX-M-1。对不同 ST 的 36 株分离株的进一步分析显示，blaCTX-M-1 位于 IncI1/ST3 质粒上。
ESBL-E 在这个肉鸡养殖场的快速传播不是由于一个特定大肠杆菌克隆的传播，而是由于携带 blaCTX-M-1 的 IncI1/ST3 质粒的水平转移，导致肉鸡中主要 ESBL-E 种群发生变化。
