Kromann Sofie, Baig Sharmin, Olsen Rikke Heidemann, Edslev Sofie Marie, Thøfner Ida, Bojesen Anders Miki, Jensen Henrik Elvang, Stegger Marc
Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg C, Denmark; DanHatch Denmark A/S, Rugerivej 26, 9760 Vrå, Denmark.
Statens Serum Institut, Department of Bacteria, Parasites and Fungi, Artillerivej 5, 2300 Copenhagen, Denmark.
Vet Microbiol. 2023 May;280:109696. doi: 10.1016/j.vetmic.2023.109696. Epub 2023 Feb 19.
Escherichia coli constitutes a major challenge to poultry even when the prevalence of colibacillosis is low. Additionally, specific E. coli strains can severely enhance the detrimental effects on productivity, animal welfare and antimicrobial use. In 2019-2020, a dramatic increase in colibacillosis occurred among Danish broilers causing late-onset mortality and high slaughter condemnations. In the present study, the pathology and causative E. coli-types were characterised. Furthermore, the outbreak-related strains were compared to isolates from concurrent "background" colibacillosis. During the study, 1039 birds were subjected to a comprehensive post-mortem examination, and a total of 349 E. coli isolates were sequenced and characterised by multi-locus sequence typing, virulence and resistance gene presence, plasmid replicon content and phylogenetic analysis. Productivity data from outbreak flocks revealed a mortality of 6.34% ± 3.74 and a condemnation of 5.04% ± 3.67. Contrary, the numbers were 3.18% ± 1.57% and 1.02% ± 0.4 among non-outbreak flocks, respectively. Major lesions were cellulitis (46.82%), airsacculitis (67.63%), pericarditis (55.49%), perihepatitis (41.04%) and femoral head necrosis with physeal/metaphyseal involvement (44.51%). Among non-outbreak broilers, the prevalence was 4.46%, 7.64%, 7.01%, 3.82% and 8.28%, respectively. ST23 and ST101 dominated heavily in outbreak flocks, whereas non-outbreak related isolates consisted of various other STs. A low level of resistance markers was evident, except in few multidrug-resistant isolates. Within ST23 and ST101, 13 and 12 virulence genes were significantly over-represented compared to non-outbreak isolates. In conclusion, clonal lineages were documented as the cause of a devastating outbreak of colibacillosis with great prospects for future interventions.
即使大肠杆菌病的发病率很低，大肠杆菌对家禽来说仍是一个重大挑战。此外，特定的大肠杆菌菌株会严重加剧对生产力、动物福利和抗菌药物使用的不利影响。在2019 - 2020年期间，丹麦肉鸡中大肠杆菌病急剧增加，导致后期死亡率和高屠宰废弃率。在本研究中，对病理和致病性大肠杆菌类型进行了特征描述。此外，将与疫情相关的菌株与同期“背景”大肠杆菌病的分离株进行了比较。在研究过程中，对1039只鸡进行了全面的尸检，并对总共349株大肠杆菌分离株进行了测序，并通过多位点序列分型、毒力和耐药基因存在情况、质粒复制子含量和系统发育分析进行了特征描述。疫情鸡群的生产力数据显示死亡率为6.34%±3.74，废弃率为5.04%±3.67。相反，非疫情鸡群的这两个数字分别为3.18%±1.57%和1.02%±0.4。主要病变为蜂窝织炎（46.82%）、气囊炎（67.63%）、心包炎（55.49%）、肝周炎（41.04%）和累及骨骺/干骺端的股骨头坏死（44.51%）。在非疫情肉鸡中，患病率分别为4.46%、7.64%、7.01%、3.82%和8.28%。ST23和ST101在疫情鸡群中占主导地位，而非疫情相关分离株则由各种其他ST型组成。除了少数多重耐药分离株外，耐药标记水平较低。与非疫情分离株相比，ST23和ST101内分别有13个和12个毒力基因显著富集。总之，克隆谱系被证明是一场毁灭性大肠杆菌病疫情的病因，为未来的干预提供了广阔前景。
