Institute of Poultry Diseases, Freie Universität Berlin, 14163 Berlin, Germany.
Leibniz Institute for Zoo and Wildlife Research, 10315 Berlin, Germany.
Biomed Res Int. 2019 Oct 30;2019:6147695. doi: 10.1155/2019/6147695. eCollection 2019.
Virulence-associated traits have frequently been studied in enterococci and are considered to contribute towards the pathogenicity of infections. In the present study, isolates were collected during diagnostic investigations from meat turkeys in Germany. Twenty-eight isolates of three different species were analyzed for five selected putative virulence traits to understand their potential role in the pathogenicity using the chicken embryo lethality assay. Ten , ten , and eight isolates were examined for the presence of common virulence genes and their phenotypic expression, namely, the cytolysin operon, five individual genes ( , , , , and ), gelatinase (), hyaluronidase ( ), aggregation substance (), and enterococcal surface protein (). The isolates showed significant species-dependent differences in the presence of genotypic traits ( < 0.001 by Fisher's exact test; Cramer's = 0.68). At least one gene and up to three virulence traits were found in , while six isolates and one isolate did not display any virulence-associated pheno- or genotype. More than half of the isolates ( = 15) harbored the gene, but only ( = 10) expressed the gelatinase activity . The gene was found in five isolates only, while seven isolates showed the hyaluronidase activity in the phenotypic assay. In Cramer's statistic, a moderate association was indicated for species ( ≤ 0.35) or genotype ( < 0.43) and the results from the embryo lethality assay, but the differences were not significant. All isolates were less virulent with mortality rates ranging between 0 and 30%. Two isolates were highly virulent, harboring the whole -operon as well as and genes. Likewise, one isolate caused high embryo mortality but did not harbor any of the investigated virulence genes. For the first time, isolates of three different species collected from diseased turkeys were investigated for their virulence properties in comparison. The results differed markedly between the species, with harboring the majority of investigated genes and virulence traits. However, the genotype did not entirely correlate with the phenotype or the isolates' virulence potential and pathogenicity for chicken embryos.
毒力相关特征在肠球菌中经常被研究，并被认为有助于感染的致病性。在本研究中，从德国的肉用火鸡的诊断研究中收集了 株分离株。分析了三种不同 种的 28 株分离株的五个选定的假定毒力特征，以了解它们在致病性方面的潜在作用，方法是使用鸡胚致死测定。检查了 10 株 、10 株 和 8 株 分离株是否存在常见的毒力基因及其表型表达，即细胞毒素操纵子、5 个单个 基因（ 、 、 、 和 ）、明胶酶（）、透明质酸酶（ ）、聚集物质（）和肠球菌表面蛋白（）。种间存在基因型特征存在显著差异（Fisher 精确检验， < 0.001；Cramer's = 0.68）。在 中发现了至少一个基因和最多三个毒力特征，而 6 株 分离株和 1 株 分离株没有表现出任何与毒力相关的表型或基因型。超过一半的 分离株（ = 15）携带 基因，但只有 （ = 10）表达明胶酶活性。 基因仅在 5 株 分离株中发现，而 7 株分离株在表型测定中显示透明质酸酶活性。在 Cramer's 统计中，物种（ ≤ 0.35）或基因型（ < 0.43）与胚胎致死测定结果之间存在中度关联，但差异无统计学意义。所有 分离株的死亡率在 0%至 30%之间，毒力较低。两株 分离株高度毒力，携带整个 操纵子以及 和 基因。同样，一株 分离株引起高胚胎死亡率，但不携带任何研究的毒力基因。首次比较研究了从患病火鸡中分离的三种不同种的 分离株的毒力特性。结果在 种之间有明显差异， 种携带了大多数研究的基因和毒力特征。然而，基因型并不完全与表型或分离株的毒力潜力和对鸡胚的致病性相关。
