College of Animal Science and Technology, Shandong Agricultural University, Tai'an City 271018, Shandong Province, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Tai'an City 271018, Shandong Province, China; Sino-German Cooperative Research Centre for Zoonosis of Animal Origin Shandong Province, Shandong Agricultural University, Tai'an City 271018, Shandong Province, China.
Qingdao Key Laboratory of Livestock & Poultry Pathogen Biotechnology, Qingdao Jiazhi Biotechnology Co., Ltd., Qingdao 266100, China.
Poult Sci. 2023 Jul;102(7):102759. doi: 10.1016/j.psj.2023.102759. Epub 2023 Apr 28.
Infectious serositis is a common disease caused by Riemerella anatipestifer (R. anatipestifer) in ducks, characterized by respiratory distress, septicemia, and neurological symptoms. In this study, 1,020 samples (brain and liver) were collected from ducks with suspected R. anatipestifer infection from March 2020 to March 2022 in Shandong Province, of which 171 R. anatipestifer strains were identified by PCR and isolation culture. The serotype of all strains was analyzed, and 74 strains were subjected to drug sensitivity tests and drug resistance genes detection. The results showed that the overall prevalence rate of R. anatipestifer in Shandong Province was 16.7% (171/1,020), with most strains coming from brain samples of ducklings under 3-mo old collected from September to December each year. Histopathological examination showed that heart vessels of the diseased duck were highly dilated and filled with red blood cells, with obvious fibrin exudates outside the pericardium, and fatty degeneration of liver cells. There were 45 strains of serotype 1, 45 strains of serotype 2, 2 strains of serotype 4, 33 strains of serotype 6, 44 strains of serotype 7, and 2 strains of serotype 10. The minimum inhibitory concentration (MIC) of 10 common antibiotics against 74 representative strains was determined by the agar dilution method. It was found that 74 strains had the most severe resistance to gentamicin (77%) and fully susceptible to ceftriaxone, but the 81.1% isolated strains were multidrug resistant. Resistance genes testing of 74 R. anatipestifers showed that tetracycline resistance gene tet X had the highest detection rate of 95.9%, followed by macrolide resistance gene ermF with 77%, and the rate of β-lactam resistance gene bla is the lowest (10.8%). The animal experiment of 4 R. anatipestifer strains with different serotypes showed that they had strong pathogenicity to 7-day-old ducklings, which could cause nervous symptoms, and the mortality rate was 58% to 70%. The autopsy showed obvious pathological changes. These findings of this study on R. anatipestifer will help us to understand the latest prevalence, drug resistance characteristics, and pathogenicity of R. anatipestifer in Shandong, China, and provide a scientific guide for the treatment and control of the disease.
传染性浆膜炎是一种由鸭传染性浆膜炎（Riemerella anatipestifer，R. anatipestifer）引起的常见疾病，以呼吸困难、败血症和神经症状为特征。在这项研究中，2020 年 3 月至 2022 年 3 月期间，从山东省疑似感染 R. anatipestifer 的鸭中采集了 1020 份（脑和肝）样本，其中 171 株通过 PCR 和分离培养鉴定为 R. anatipestifer 株。分析了所有菌株的血清型，并对 74 株进行了药敏试验和耐药基因检测。结果表明，山东省 R. anatipestifer 的总流行率为 16.7%（171/1020），大部分菌株来自每年 9 月至 12 月采集的 3 月龄以下雏鸭的脑组织样本。组织病理学检查显示，患病鸭的心脏血管高度扩张，充满红细胞，心包外有明显的纤维蛋白渗出物，肝细胞脂肪变性。有 45 株血清型 1、45 株血清型 2、2 株血清型 4、33 株血清型 6、44 株血清型 7 和 2 株血清型 10。采用琼脂稀释法测定 10 种常用抗生素对 74 株代表性菌株的最低抑菌浓度（MIC）。结果发现，74 株对庆大霉素的耐药性最为严重（77%），对头孢曲松完全敏感，但分离株的 81.1%为多药耐药。对 74 株 R. anatipestifer 的耐药基因检测显示，四环素耐药基因 tet X 的检出率最高（95.9%），其次是大环内酯类耐药基因 ermF（77%），β-内酰胺类耐药基因 bla 的检出率最低（10.8%）。4 株不同血清型的 R. anatipestifer 动物实验表明，它们对 7 日龄雏鸭具有很强的致病性，可引起神经症状，死亡率为 58%至 70%。剖检显示明显的病理变化。本研究对山东省 R. anatipestifer 的最新流行情况、耐药性特征和致病性的研究，将有助于我们了解中国山东省 R. anatipestifer 的最新流行情况、耐药性特征和致病性，为该病的治疗和控制提供科学指导。
