Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, University of Basel, Petersgraben 4, 4031, Basel, Switzerland.
Swiss Tropical and Public Health Institute, Basel, Switzerland.
Antimicrob Resist Infect Control. 2023 Apr 21;12(1):38. doi: 10.1186/s13756-023-01242-y.
We sought to decipher transmission pathways in healthcare-associated infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within our hospital by epidemiological work-up and complementary whole genome sequencing (WGS). We report the findings of the four largest epidemiologic clusters of SARS-CoV-2 transmission occurring during the second wave of the pandemic from 11/2020 to 12/2020.
At the University Hospital Basel, Switzerland, systematic outbreak investigation is initiated at detection of any nosocomial case of SARS-CoV-2 infection, as confirmed by polymerase chain reaction, occurring more than five days after admission. Clusters of nosocomial infections, defined as the detection of at least two positive patients and/or healthcare workers (HCWs) within one week with an epidemiological link, were further investigated by WGS on respective strains.
The four epidemiologic clusters included 40 patients and 60 HCWs. Sequencing data was available for 70% of all involved cases (28 patients and 42 HCWs), confirmed epidemiologically suspected in house transmission in 33 cases (47.1% of sequenced cases) and excluded transmission in the remaining 37 cases (52.9%). Among cases with identical strains, epidemiologic work-up suggested transmission mainly through a ward-based exposure (24/33, 72.7%), more commonly affecting HCWs (16/24, 66.7%) than patients (8/24, 33.3%), followed by transmission between patients (6/33, 18.2%), and among HCWs and patients (3/33, 9.1%, respectively two HCWs and one patient).
Phylogenetic analyses revealed important insights into transmission pathways supporting less than 50% of epidemiologically suspected SARS-CoV-2 transmissions. The remainder of cases most likely reflect community-acquired infection randomly detected by outbreak investigation. Notably, most transmissions occurred between HCWs, possibly indicating lower perception of the risk of infection during contacts among HCWs.
我们通过流行病学调查和补充全基因组测序（WGS），试图破译我们医院内与严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）相关的医院获得性感染的传播途径。我们报告了 2020 年 11 月至 12 月大流行第二波期间发生的 SARS-CoV-2 传播的四个最大的流行病学聚集的发现。
在瑞士巴塞尔大学医院，一旦发现任何经聚合酶链反应确认的住院后超过五天的 SARS-CoV-2 感染的医院获得性病例，就会启动系统的暴发调查。将在一周内检测到至少两名阳性患者和/或医护人员（HCW）且具有流行病学联系的医院内感染聚集定义为簇，对各自的菌株进行 WGS 进一步调查。
这四个流行病学聚集包括 40 名患者和 60 名 HCW。对所有涉及病例的 70%（28 名患者和 42 名 HCW）进行了测序数据，在 33 例（测序病例的 47.1%）中证实了在流行病学上疑似院内传播，并在其余 37 例（52.9%）中排除了传播。在具有相同菌株的病例中，流行病学调查表明传播主要通过病房暴露（24/33，72.7%），更常见于 HCW（16/24，66.7%）而不是患者（8/24，33.3%），其次是患者之间（6/33，18.2%）以及 HCW 和患者之间（3/33，9.1%，分别为两名 HCW 和一名患者）。
系统发育分析提供了对支持不到 50%的流行病学疑似 SARS-CoV-2 传播途径的重要见解。其余病例很可能反映了社区获得性感染，这些感染是通过暴发调查随机检测到的。值得注意的是，大多数传播发生在 HCW 之间，这可能表明 HCW 之间的感染风险意识较低。
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