UCIBIO/REQUIMTE, Departamento de Ciências Biológicas, Laboratório de Microbiologia, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal.
Servicio de Microbiología, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain.
J Antimicrob Chemother. 2018 Feb 1;73(2):306-319. doi: 10.1093/jac/dkx387.
The criteria for identification of Enterococcus faecium (Efm) with the ability to cause human infections are currently being debated by the European Food Safety Authority (EFSA). Strains that have an MIC of ampicillin of ≤ 2 mg/L and lack IS16/esp/hyl genes should be regarded as safe for use as feed additives in animal nutrition, despite the lack of knowledge about putative virulence marker (PVM) distribution in community Efm. We analysed the distribution of major PVM and ampicillin phenotypes in large Efm collections to investigate further the safety of strains from a public health perspective.
Thirty-three PVM were assessed by PCR/sequencing among clonally disparate Efm (n = 328; 1986-2015) from different origins. We analysed ampicillin susceptibility (Etest/broth microdilution) according to EUCAST guidelines, clonal relationship (MLST) and genomic location of PVM (S1-PFGE/hybridization).
Infection-derived Efm were more enriched in PVM and the increase in ampicillin MIC was positively correlated with an enrichment in different PVM. PVM coding for surface (esp/sgrA/ecbA/complete acm) and pili proteins, or others enhancing colonization (hyl/ptsD/orf1481) or plasticity (IS16), were strongly associated with clinical Efm (mostly clade A1), but also observed in clades A2/B at different rates. ptsD was a good marker of ampicillin-resistant Efm. ptsD, IS16, orf1481, sgrA and hospital variants of complete pili gene clusters are proposed as markers to assess the safety of Efm strains.
Our study expands on the distribution of PVM in diverse Efm lineages and demonstrates the enrichment in infection-derived strains of PVM not previously included in EFSA's list of Efm safety criteria. The evidence of relevant Efm infection markers can impact the risk assessment of Efm strains in different public health contexts.
欧洲食品安全局（EFSA）目前正在争论肠球菌粪亚种（Efm）引起人类感染的鉴定标准。MIC 值为氨苄青霉素≤2mg/L 且缺乏 IS16/esp/hyl 基因的菌株应被视为可安全用于动物营养的饲料添加剂，尽管缺乏有关社区 Efm 中假定毒力标记（PVM）分布的知识。我们分析了大型 Efm 集合中主要 PVM 和氨苄青霉素表型的分布，以从公共卫生角度进一步研究菌株的安全性。
通过 PCR/测序在来自不同来源的克隆差异 Efm（n=328；1986-2015 年）中评估了 33 种 PVM。我们根据 EUCAST 指南分析了氨苄青霉素敏感性（Etest/肉汤微量稀释法）、克隆关系（MLST）和 PVM 的基因组位置（S1-PFGE/杂交）。
感染衍生的 Efm 中 PVM 更为丰富，氨苄青霉素 MIC 的增加与不同 PVM 的富集呈正相关。编码表面（esp/sgrA/ecbA/完整 acm）和菌毛蛋白的 PVM 或其他增强定植（hyl/ptsD/orf1481）或可塑性（IS16）的 PVM 与临床 Efm（主要是 A1 群）强烈相关，但在不同比例的 A2/B 群中也有观察到。ptsD 是氨苄青霉素耐药 Efm 的良好标记。ptsD、IS16、orf1481、sgrA 和完整菌毛基因簇的医院变异体被提议作为评估 Efm 菌株安全性的标记。
我们的研究扩展了不同 Efm 谱系中 PVM 的分布，并证明了在感染衍生的菌株中 PVM 的富集，这些 PVM 以前未包含在 EFSA 的 Efm 安全标准清单中。相关 Efm 感染标记的证据可能会影响不同公共卫生背景下 Efm 菌株的风险评估。
