Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, PO Box 80.165, 3508 TD Utrecht, The Netherlands.
J Antimicrob Chemother. 2013 Nov;68(11):2468-76. doi: 10.1093/jac/dkt219. Epub 2013 Jun 11.
To assess the within-farm dynamics of extended-spectrum β-lactamase (ESBL)/AmpC-producing Escherichia coli in veal calves.
Three veal-calf fattening farms were screened. Faecal samples from all calves within a compartment (109-150 per farm) were taken upon arrival on the farm (T0) and after 3, 6, 8 and 10 weeks (T3-T10). ESBL/AmpC genes were characterized by PCR and sequencing. Plasmids were characterized by transformation, PCR-based replicon typing and plasmid multilocus sequence typing (MLST). E. coli genotypes were analysed by MLST.
At T0 the prevalence of ESBL/AmpC-producing E. coli ranged from 18% to 26%. These were predominantly isolates carrying blaCTX-M-1 and blaCTX-M-15 genes, located on various plasmids and E. coli sequence types (STs). Farm 1 was negative for ESBL/AmpC-producing E. coli after T0. Farm 2 showed an increase up to 37% at T3, which subsequently decreased gradually to 0% at T10. The presence from T3 to T10 on farm 2 was mainly caused by the clonal spread of a multiresistant E. coli ST57 harbouring blaCTX-M-14 on an IncF F2:A-:B- plasmid. Farm 3 showed a gradual decrease in prevalence to 1.4% at T10, with a relative increase of the identical clonal variant as shown for farm 2. A second clonal variant found in farm 3 was a multiresistant E. coli ST10 harbouring blaCTX-M-14 on an IncK plasmid.
The prevalence of ESBL/AmpC-producing E. coli decreased over time. A clonal spread was observed on farm 2 and farm 3, illustrative of the complex dynamics probably associated with the use of antimicrobials.
评估产extended-spectrum β-lactamase (ESBL)/AmpC 的大肠杆菌在小牛肉犊牛中的农场内动态。
对 3 个小牛肉育肥农场进行筛查。每个畜栏（每个农场 109-150 头）的所有小牛在抵达农场时（T0）以及 3、6、8 和 10 周后（T3-T10）采集粪便样本。通过 PCR 和测序来鉴定 ESBL/AmpC 基因。通过转化、基于 PCR 的复制子分型和质粒多位点序列分型（MLST）来鉴定质粒。通过 MLST 分析大肠杆菌基因型。
在 T0，产 ESBL/AmpC 大肠杆菌的流行率为 18%至 26%。这些主要是携带 blaCTX-M-1 和 blaCTX-M-15 基因的分离株，位于各种质粒和大肠杆菌序列型（ST）上。T0 后，1 号农场无产 ESBL/AmpC 大肠杆菌。2 号农场在 T3 时增加到 37%，随后逐渐降至 T10 时的 0%。从 T3 到 T10，2 号农场的存在主要是由携带 blaCTX-M-14 的多药耐药大肠杆菌 ST57 的克隆传播引起的，该 ST57 位于 IncF F2:A-:B-质粒上。3 号农场的流行率逐渐降至 T10 时的 1.4%，与 2 号农场一样，相同的克隆变异相对增加。在 3 号农场发现的第二种克隆变异是携带 blaCTX-M-14 的多药耐药大肠杆菌 ST10，该 ST10 位于 IncK 质粒上。
产 ESBL/AmpC 大肠杆菌的流行率随时间逐渐降低。在 2 号和 3 号农场观察到了克隆传播，这表明与使用抗生素相关的复杂动态。
