Achermann Yvonne, Seidl Kati, Kuster Stefan P, Leimer Nadja, Durisch Nina, Ajdler-Schäffler Evelyne, Karrer Stephan, Senn Gabriela, Holzmann-Bürgel Anne, Wolfensberger Aline, Leone Antonio, Arlettaz Romaine, Zinkernagel Annelies S, Sax Hugo
1Division of Infectious Diseases and Hospital Epidemiology,University Hospital of Zurich,University of Zurich,Zurich,Switzerland.
2Division of Neonatology,University Hospital of Zurich,University of Zurich,Zurich,Switzerland.
Infect Control Hosp Epidemiol. 2015 Nov;36(11):1305-12. doi: 10.1017/ice.2015.184. Epub 2015 Aug 20.
In-hospital transmission of methicillin-susceptible Staphylococcus aureus (MSSA) among neonates remains enigmatic. We describe the epidemiology of MSSA colonization and infection in a 30-bed neonatal ward.
Multimodal outbreak investigation
A public 800-bed tertiary care university hospital in Switzerland
Investigations in 2012-2013, triggered by a MSSA infection cluster, included prospective MSSA infection surveillance, microbiologic screening of neonates and environment, onsite observations, and a prospective cohort study. MSSA isolates were characterized by pulsed-field gel electrophoresis (PFGE) and selected isolates were examined for multilocus sequence type (MLST) and virulence factors.
Among 726 in 2012, 30 (4.1%) patients suffered from MSSA infections including 8 (1.1%) with bacteremia. Among 655 admissions in 2013, 13 (2.0%) suffered from MSSA infections including 2 (0.3%) with bacteremia. Among 177 neonates screened for S. aureus carriage, overall 77 (44%) tested positive. A predominant PFGE-1-ST30 strain was identified in 6 of 30 infected neonates (20%) and 30 of 77 colonized neonates (39%). This persistent clone was pvl-negative, tst-positive and belonged to agr group III. We found no environmental point source. MSSA carriage was associated with central vascular catheter use but not with a particular midwife, nurse, physician, or isolette. Observed healthcare worker behavior may have propagated transmission via hands and fomites. Despite multimodal interventions, clonal transmission and colonization continued and another clone, PFGE-6-ST5, became predominant.
Hospital-acquired MSSA clones represent a high proportion of MSSA colonization but not MSSA infections in neonate inpatients. In contrast to persisting MSSA, transmission infection rates decreased concurrently with interventions. It remains to be established whether eradication of hospital-acquired MSSA strains would reduce infection rates further.
耐甲氧西林金黄色葡萄球菌（MSSA）在新生儿中的院内传播情况仍不明朗。我们描述了一家拥有30张床位的新生儿病房中MSSA定植和感染的流行病学情况。
多模式暴发调查
瑞士一家拥有800张床位的公立三级护理大学医院
2012 - 2013年，由MSSA感染聚集事件引发的调查包括前瞻性MSSA感染监测、新生儿及环境的微生物筛查、现场观察以及一项前瞻性队列研究。MSSA分离株通过脉冲场凝胶电泳（PFGE）进行特征分析，部分分离株进行多位点序列分型（MLST）及毒力因子检测。
2012年的726名患者中，30例（4.1%）发生MSSA感染，其中8例（1.1%）为菌血症。2013年的655名入院患者中，13例（2.0%）发生MSSA感染，其中2例（0.3%）为菌血症。在177名筛查金黄色葡萄球菌携带情况的新生儿中，共有77例（44%）检测呈阳性。在30例感染新生儿中的6例（20%）以及77例定植新生儿中的30例（39%）中鉴定出一种主要的PFGE - 1 - ST30菌株。这种持续存在的克隆株pvl阴性、tst阳性，属于agr III组。我们未发现环境中的点源。MSSA定植与中心血管导管的使用有关，但与特定的助产士、护士、医生或保温箱无关。观察到的医护人员行为可能通过手和污染物传播了感染。尽管采取了多模式干预措施，克隆传播和定植仍在继续，另一种克隆株PFGE - 6 - ST5成为主要菌株。
医院获得性MSSA克隆株在新生儿住院患者的MSSA定植中占很大比例，但在MSSA感染中所占比例不大。与持续存在的MSSA不同，传播感染率随着干预措施的实施而同时下降。医院获得性MSSA菌株的根除是否会进一步降低感染率仍有待确定。
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