Department of Environmental Health and Science, University of Michigan, Ann Arbor, Michigan; Applied Research Center, NSF International, Ann Arbor, Michigan.
Department of Epidemiology, University of Michigan, Ann Arbor, Michigan.
Am J Infect Control. 2018 Jun;46(6):620-626. doi: 10.1016/j.ajic.2017.12.002. Epub 2018 Feb 12.
Healthcare-associated infections (HAIs) affect millions of patients every year. Pathogen transmission via fomites and healthcare workers (HCWs) contribute to the persistence of HAIs in hospitals. A critical parameter needed to assess risk of environmental transmission is the pathogen transfer efficiency between fomites and fingers. Recent studies have shown that pathogen transfer is not symmetric. In this study,we evaluated how the commonly used assumption of symmetry in transfer efficiency changes the dynamics of pathogen movement between patients and rooms and the exposures to uncolonized patients.
We developed and analyzed a deterministic compartmental model of Acinetobacter baumannii describing the contact-mediated process among HCWs, patients, and the environment. We compared a system using measured asymmetrical transfer efficiency to 2 symmetrical transfer efficiency systems.
Symmetric models consistently overestimated contamination levels on fomites and underestimated contamination on patients and HCWs compared to the asymmetrical model. The magnitudes of these miscalculations can exceed 100%. Regardless of the model, relative percent reductions in contamination declined after hand hygiene compliance reached approximately 60% in the large fomite scenario and 70% in the small fomite scenario.
This study demonstrates how healthcare facility-specific data can be used for decision-making processes. We show that the incorrect use of transfer efficiency data leads to biased effectiveness estimates for intervention strategies. More accurate exposure models are needed for more informed infection prevention strategies.
每年有数百万患者受到医疗保健相关感染（HAI）的影响。病原体通过污染物和医护人员（HCW）传播是导致医院中 HAI 持续存在的原因之一。评估环境传播风险的一个关键参数是污染物与手指之间病原体转移效率。最近的研究表明，病原体转移并非对称的。在这项研究中，我们评估了在转移效率中常见的对称假设如何改变病原体在患者和房间之间以及未定植患者之间的移动动力学和暴露情况。
我们开发并分析了一个描述不动杆菌属接触介导过程的确定型隔室模型，该模型描述了 HCW、患者和环境之间的接触介导过程。我们将使用测量得到的非对称转移效率的系统与 2 个对称转移效率系统进行了比较。
与不对称模型相比，对称模型始终高估了污染物在污染物上的污染水平，并低估了患者和 HCW 上的污染水平。这些错误计算的幅度可能超过 100%。无论模型如何，在手卫生依从性达到大污染物场景中的约 60%和小污染物场景中的 70%左右后，污染的相对百分比减少都会下降。
这项研究表明了如何使用特定于医疗保健设施的数据进行决策过程。我们表明，转移效率数据的不正确使用会导致干预策略的有效性估计产生偏差。需要更准确的暴露模型来制定更明智的感染预防策略。
