Background Enterococcus faecium is part of the human gastrointestinal flora but may act as opportunistic pathogen. Environmental persistence, high colonization capability and diverse intrinsic and acquired resistance mechanisms make it especially successful in nosocomial high-risk settings. In March 2014, an outbreak of Linezolid resistant Enterococcus faecium (LREfm) was observed at the hematooncology department of a tertiary care center in Upper Austria. Methods We report on the outbreak investigation together with the whole genome sequencing (WGS)-based typing results including also non-outbreak LREfm and susceptible isolates. Results The 54 investigated isolates could be divided in six clusters based on cgMLST. Cluster one comprised LREfm isolates of genotype ST117 and CT24, which was identified as the causative clone of the outbreak. In addition, the detection of four other clusters comprising isolates originating from hematooncology patients but also at other hospitals, pointed to LREfm transmission between local healthcare facilities. LREfm patients (n = 36) were typically at risk for acquisition of nosocomial pathogens because of immunosuppression, frequent hospitalization and antibiotic therapies. Seven of these 36 patients developed LREfm infection but were successfully treated. After termination of the initial outbreak, sporadic cases occurred despite a bundle of applied outbreak control interventions. Conclusions WGS proved to be an effective tool to differentiate several LREfm clusters in an outbreak. Active screening for LREfm is important in a high-risk setting such as hematooncology, where multiple introductions are possible and occur despite intensified infection control measures.

中文翻译：

---

上奥地利州因利奈唑胺耐药的肠球菌引起的医院暴发。

背景粪肠球菌是人类胃肠道菌群的一部分，但可能是机会病原体。环境持久性，高定殖能力以及多样的内在和后天抵抗机制使其在医院高危环境中尤其成功。2014年3月，在上奥地利州一家三级护理中心的血液学部门发现了对Linezolid耐药的粪肠球菌（LREfm）的爆发。方法我们报告了暴发调查以及基于全基因组测序（WGS）的分型结果，包括非暴发LREfm和易感分离株。结果根据cgMLST可以将54株分离株分为6个类群。聚类一包含基因型为ST117和CT24的LREfm分离株，其被确定为暴发的致病性克隆。此外，对包括血液病学患者以及其他医院的分离株在内的其他四个簇的检测结果表明，LREfm在当地医疗机构之间传播。LREfm患者（n = 36）通常由于免疫抑制，频繁住院和抗生素治疗而有获得医院病原体的风险。这36例患者中有7例发生LREfm感染，但得到了成功治疗。最初的暴发终止后，尽管实施了一系列的暴发控制干预措施，但仍发生了零星病例。结论WGS被证明是在暴发中区分多个LREfm集群的有效工具。积极筛查LREfm在高风险环境（例如血液病学，