Department of Veterinary Sciences, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences in Prague, Prague, Czech Republic.
Veterinary Clinic of MVDr. Martina Načeradská, Prague, Czech Republic.
PLoS One. 2021 Jun 9;16(6):e0251968. doi: 10.1371/journal.pone.0251968. eCollection 2021.
Cilia-associated respiratory bacillus (CARB; now known as Filobacterium rodentium gen. nov., sp. nov.) is a primary pathogen of rodents. A CARB-like organism was reported in post-mortem lung samples of cats using light and electron microscopy. Here we explore by molecular procedures if a Filobacterium sp. is a part of the normal feline lower respiratory microbiome and whether it could in some cats contribute to the development of chronic bronchial disease.
A Filobacterium sp. was identified in three Czech cats clinically diagnosed as having chronic neutrophilic bronchitis. Bronchoalveolar lavage fluid (BALF) specimens obtained from these cats were subjected to panbacterial 16S rDNA PCR followed by Sanger sequencing of the V5 to V8 region. After these cats were treated with specific antimicrobials, their clinical signs resolved promptly, without recurrence. Next, BALF specimens from 13 Australian and 11 Italian cats with lower respiratory disease and an additional 16 lung samples of Italian cats who died of various causes were examined using next generation sequencing (NGS). Subsequently, a Filobacterium-specific qPCR assay was developed and used to re-test BALF specimens from the 11 Italian cats and lung tissue homogenates from the additional 16 deceased cats.
An amplicon of 548 bp with 91.24% sequence agreement with Filobacterium rodentium was obtained from all three patients, suggesting the novel Filobacterium sp. was the cause of their lower respiratory disease. The novel Filobacterium sp., which we propose to call F. felis, was detected in 3/3 Czech cats with chronic neutrophilic bronchitis, 13/13 Australian cats and 6/11 Italian cats with chronic lower respiratory disease, and 14/16 necropsy lung specimens from Italian cats. NGS and qPCR results all showed identical sequences. The Filobacterium sp. was sometimes the preponderant bacterial species in BALF specimens from cats with lower airway disease. There was an association between the presence of large numbers (greater than 105 organisms/mL) of Filobacterium and the presence of neutrophilic and/or histiocytic inflammation, although only a subset of inflammatory BALF specimens had F. felis as the preponderant organism.
The novel Filobacterium sp. comprises a finite part of the normal feline lower respiratory microbiome. Under certain circumstances it can increase in absolute and relative abundance and give rise to neutrophilic and/or histiocytic bronchitis, bronchiolitis and bronchopneumonia. These findings strongly suggest that F. felis could be an underdiagnosed cause of feline bronchial disease.
纤毛相关呼吸杆菌（CARB；现称为啮齿动物纤维杆菌属，新种）是啮齿动物的主要病原体。用光镜和电镜在猫的死后肺样本中报告了一种类似 CARB 的生物体。在这里，我们通过分子程序探索是否有一种纤维杆菌是猫下呼吸道微生物组的正常组成部分，以及它是否会在某些猫中导致慢性支气管疾病的发展。
在临床上被诊断为患有慢性嗜中性支气管炎的三只捷克猫中鉴定出一种纤维杆菌。从这些猫中获得的支气管肺泡灌洗液（BALF）标本进行了泛细菌 16S rDNA PCR，然后对 V5 至 V8 区进行 Sanger 测序。在这些猫接受特定的抗菌药物治疗后，它们的临床症状迅速消退，没有复发。接下来，对 13 只澳大利亚猫和 11 只意大利猫的下呼吸道疾病以及另外 16 只死于各种原因的意大利猫的肺部样本进行了下一代测序（NGS）。随后，开发了一种纤维杆菌特异性 qPCR 检测方法，并用于重新检测 11 只意大利猫的 BALF 样本和另外 16 只死亡猫的肺组织匀浆。
从所有 3 名患者中均获得了与啮齿动物纤维杆菌具有 91.24%序列一致性的 548 bp 扩增子，表明新型纤维杆菌是其下呼吸道疾病的原因。新型纤维杆菌，我们建议将其命名为 F. felis，在 3/3 例慢性嗜中性支气管炎的捷克猫、13/13 例澳大利亚猫和 6/11 例慢性下呼吸道疾病的意大利猫以及 16 例意大利猫的尸检肺标本中均有检测到。NGS 和 qPCR 结果均显示出相同的序列。在患有下呼吸道疾病的猫的 BALF 标本中，纤维杆菌有时是主要细菌种类。尽管只有一部分炎症性 BALF 标本的优势生物体是 F. felis，但大量（大于 105 个生物体/mL）的纤维杆菌存在与中性粒细胞和/或组织细胞炎症之间存在关联。
新型纤维杆菌是猫下呼吸道微生物组的正常组成部分。在某些情况下，它的绝对和相对丰度会增加，并引起中性粒细胞和/或组织细胞性支气管炎、细支气管炎和支气管肺炎。这些发现强烈表明，F. felis 可能是猫支气管疾病的一种未被充分诊断的原因。
