Department of Laboratory Medicine, Ghent University Hospital, Ghent, Belgium.
Department of Diagnostic Sciences, Ghent University, Ghent, Belgium.
Antimicrob Resist Infect Control. 2023 Jun 19;12(1):58. doi: 10.1186/s13756-023-01261-9.
Accumulating evidence shows a role of the hospital wastewater system in the spread of multidrug-resistant organisms, such as carbapenemase producing Enterobacterales (CPE). Several sequential outbreaks of CPE on the geriatric ward of the Ghent University hospital have led to an outbreak investigation. Focusing on OXA-48 producing Citrobacter freundii, the most prevalent species, we aimed to track clonal relatedness using whole genome sequencing (WGS). By exploring transmission routes we wanted to improve understanding and (re)introduce targeted preventive measures.
Environmental screening (toilet water, sink and shower drains) was performed between 2017 and 2021. A retrospective selection was made of 53 Citrobacter freundii screening isolates (30 patients and 23 environmental samples). DNA from frozen bacterial isolates was extracted and prepped for shotgun WGS. Core genome multilocus sequence typing was performed with an in-house developed scheme using 3,004 loci.
The CPE positivity rate of environmental screening samples was 19.0% (73/385). Highest percentages were found in the shower drain samples (38.2%) and the toilet water samples (25.0%). Sink drain samples showed least CPE positivity (3.3%). The WGS data revealed long-term co-existence of three patient sample derived C. freundii clusters. The biggest cluster (ST22) connects 12 patients and 8 environmental isolates taken between 2018 and 2021 spread across the ward. In an overlapping period, another cluster (ST170) links eight patients and four toilet water isolates connected to the same room. The third C. freundii cluster (ST421) connects two patients hospitalised in the same room but over a period of one and a half year. Additional sampling in 2022 revealed clonal isolates linked to the two largest clusters (ST22, ST170) in the wastewater collection pipes connecting the rooms.
Our findings suggest long-term circulation and transmission of carbapenemase producing C. freundii clones in hospital sanitary installations despite surveillance, daily cleaning and intermittent disinfection protocols. We propose a role for the wastewater drainage system in the spread within and between rooms and for the sanitary installations in the indirect transmission via bioaerosol plumes. To tackle this problem, a multidisciplinary approach is necessary including careful design and maintenance of the plumbing system.
越来越多的证据表明，医院废水系统在传播多药耐药菌方面发挥了作用，例如碳青霉烯酶产生肠杆菌科（CPE）。在根特大学医院老年病房发生了几起连续的 CPE 暴发后，进行了暴发调查。我们专注于最常见的产 OXA-48 型柠檬酸杆菌，旨在使用全基因组测序（WGS）追踪克隆相关性。通过探索传播途径，我们希望加深理解并（重新）引入有针对性的预防措施。
2017 年至 2021 年期间进行了环境筛查（厕所水、水槽和淋浴排水）。对 53 株柠檬酸杆菌筛查分离株（30 名患者和 23 份环境样本）进行了回顾性选择。从冷冻细菌分离物中提取 DNA 并进行用于鸟枪法 WGS 的预制备。使用内部开发的方案，使用 3004 个基因座进行核心基因组多位点序列分型。
环境筛查样本的 CPE 阳性率为 19.0%（73/385）。淋浴排水样本的阳性率最高（38.2%），其次是厕所水样本（25.0%）。水槽排水样本的 CPE 阳性率最低（3.3%）。WGS 数据显示，三个源自患者样本的柠檬酸杆菌群长期共存。最大的群集（ST22）连接了 2018 年至 2021 年间在病房内传播的 12 名患者和 8 个环境分离株。在重叠时期，另一个群集（ST170）连接了 8 名患者和 4 个与同一间房相连的厕所水分离株。第三个柠檬酸杆菌群集（ST421）连接了两名在同一病房住院但时间跨度为一年半的患者。2022 年的进一步采样显示，与两个最大群集（ST22、ST170）相连的克隆分离株存在于连接房间的废水收集管道中。
尽管进行了监测、日常清洁和间歇性消毒方案，但我们的研究结果表明，碳青霉烯酶产生的柠檬酸杆菌克隆在医院卫生设施中存在长期循环和传播。我们提出废水排水系统在房间内和房间之间的传播以及卫生设施通过生物气溶胶羽流的间接传播中发挥了作用。为了解决这个问题，需要采取多学科方法，包括仔细设计和维护管道系统。
