Runcharoon Klao, Favro Margaret E, Logue Catherine M
Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens GA 30602, USA.
Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens GA 30602, USA.
Poult Sci. 2025 Feb;104(2):104722. doi: 10.1016/j.psj.2024.104722. Epub 2024 Dec 21.
Avian pathogenic Escherichia coli (APEC) is a significant cause of worldwide morbidity, mortality, and production loss in the poultry industry. Here, we characterized 115 E. coli isolates from avian-diagnosed colibacillosis cases from Georgia, USA in 2022 as part of a year two follow on surveillance using both current and a newly developed serogrouping tool (Klao9-SeroPCR). The isolates examined were classified into 18 serogroups with the majority classifying as O78, O25, O86, O2, O8, and O1 with 32 isolates classified as untypable serogroups. In this study, the Klao9-seroPCR was able to identify serogroups of 72/115 isolates (62.6 %) using the multiplex PCR assay. This diagnostic PCR assay proved to be a potential technique for the rapid identification of the most common APEC serogroups dominating in Georgia poultry. Genotyping based on detection of selected virulence genes (VAGs) found that 22.6 % of isolates did not harbor any of the targeted genes. This analysis also confirmed that the CoIV plasmid-associated genes (iroN, ompT, hlyF, iss, and aerJ,) are still frequently found among APEC isolates (54-65 %) with a slightly lower prevalence compared to the previous year's study. Phylogenetic analysis showed that the isolates belong to phylogenetic groups G (43 %), group B2 (13 %), group F (6 %), and group A (5 %). Of interest, 30 % were identified as an unknown or cryptic phylogenetic group. This study highlights that there is a shift in the APEC causing disease in birds in the state of Georgia with virulence commonly associated with the presence of the CoIV plasmid in disease strains. Of interest, the new serogrouping panel that is designed to target more common serogroups seen in Georgia has proven to be a rapid screening/ diagnostic tool for implementation in our workflow. This study highlights a need to continue to monitor the APEC serogroups in the field to apply appropriate preventive plans against colibacillosis.
禽致病性大肠杆菌（APEC）是全球家禽业发病、死亡和生产损失的重要原因。在此，我们对2022年从美国佐治亚州禽类确诊大肠杆菌病病例中分离出的115株大肠杆菌进行了特征分析，这是第二年监测的一部分，使用了当前的和新开发的血清型分类工具（Klao9-SeroPCR）。所检测的分离株被分为18个血清型，大多数为O78、O25、O86、O2、O8和O1，32株分离株被分类为不可分型血清型。在本研究中，Klao9-seroPCR能够使用多重PCR检测法鉴定72/115株分离株（62.6%）的血清型。这种诊断性PCR检测法被证明是一种快速鉴定佐治亚州家禽中占主导地位的最常见APEC血清型的潜在技术。基于选定毒力基因（VAGs）检测的基因分型发现，22.6%的分离株未携带任何目标基因。该分析还证实，与CoIV质粒相关的基因（iroN、ompT、hlyF、iss和aerJ）在APEC分离株中仍频繁出现（54-65%），与前一年的研究相比，流行率略低。系统发育分析表明，分离株属于系统发育群G（43%）、群B2（13%）、群F（6%）和群A（5%）。有趣的是，30%被鉴定为未知或隐秘的系统发育群。这项研究突出表明，佐治亚州导致禽类发病的APEC发生了变化，毒力通常与疾病菌株中CoIV质粒的存在有关。有趣的是，旨在针对佐治亚州更常见血清型的新血清型分类面板已被证明是一种可在我们的工作流程中实施的快速筛选/诊断工具。这项研究强调需要继续监测现场的APEC血清型，以便实施针对大肠杆菌病的适当预防计划。
