A septicaemic disease outbreak caused by Pasteurella multocida at a zoo in Western Australia (Zoo A) occurred in a resident group of squirrel gliders (Petaurus norfolcensis) following the introduction of two squirrel gliders imported from another zoo (Zoo B). P. multocida isolates obtained from the affected animals and asymptomatic, cohabiting marsupials at both zoos were typed via lipopolysaccharide outer core biosynthesis locus (LPS) typing, repetitive extragenic palindromic PCR (Rep-PCR) typing, and multilocus sequence typing (ST). Investigation of isolate relatedness via whole genome sequencing (WGS) and phylogenomic analysis found that the outbreak isolates shared the same genetic profile as those obtained from the imported gliders and the positive marsupials at Zoo B. Phylogenomic analysis demonstrated that these isolates belonged to the same clone (named complex one), confirming that the outbreak strain originated at Zoo B. As well, the carriage of multiple different strains of this pathogen in a range of marsupials in a zoo setting has been demonstrated. Importantly, the genomic investigation identified a missense mutation in the latB, a structural LPS gene, resulting in introduction of an immediate stop codon in the isolates carried by asymptomatic squirrel gliders in Zoo B. The identified diversity in the latB gene of LPS outer core biosynthesis loci of these isolates is consistent with a novel phase variable mechanism for virulence in P. multocida.

Our study demonstrates the benefit of WGS and bioinformatics analysis in epidemiological investigations of pasteurellosis and its potential to reveal unexpected insights into bacterial virulence.

在引进了从另一家动物园（动物园B）进口的两只松鼠滑翔机后，在一个居住的松鼠滑翔机（Petaurus norfolcensis）居民群中发生了由多杀巴斯德氏菌引起的败血病暴发。多杀疫霉通过脂多糖外核心生物合成位点（LPS）分型，重复性外基因回文PCR（Rep-PCR）分型和多基因座序列分型（ST）对来自两个动物园的患病动物和无症状，有同居有袋动物的分离株进行分型。通过全基因组测序（WGS）和系统进化分析对分离株的相关性进行调查后发现，暴发分离株与从进口滑翔机和Zoo B的阳性有袋动物获得的基因具有相同的遗传谱。系统学分析表明，这些分离株属于同一克隆（命名为复合物一），确认该暴发菌株起源于动物园B。此外，已经证明在动物园环境中，该病原体的多种不同菌株在一系列有袋动物中的携带。重要的，latB，一种结构性LPS基因，导致在动物园B的无症状松鼠滑翔机携带的分离物中引入了立即终止密码子。这些分离物的LPS外核心生物合成基因座的latB基因中鉴定出的多样性与新型相变一致多杀疟原虫毒力的机制。

我们的研究证明了WGS和生物信息学分析在巴氏杆菌病流行病学调查中的优势，以及揭示细菌毒力的意料之外的潜力。