Transfer and Decontamination of <i>S</i>. <i>aureus</i> in Transmission Routes Regarding Hands and Contact Surfaces

Hand hygiene, cleaning and disinfection are pre-requirements for hygiene management in hospital settings and the food industry. In order to facilitate risk management, different contamination scenarios and interventions need to be evaluated. In the present study data on transfer rates and reductions of Staphylococcus aureus were provided in an experimental set-up using artificial skin. Using this methodology, test persons were not exposed with pathogenic bacteria. An exposure assessment model was developed and applied to evaluate different contamination routes and hygiene interventions. The transfer rates of S. aureus from inoculated VITRO-SKIN® to fomites were calculated from blotting series. The VITRO-SKIN® was more prone to spread bacteria than fomites. When different surfaces were cleaned, the reduction of S. aureus varied between <1 and 7 log CFU. It could not be concluded that a certain coupon material, cleaning agent, cleaning wipe, soiling or humidity consistently resulted in a high or low reduction of S. aureus. The reduction of S. aureus and E. coli during hand washing was evaluated on artificial skin, VITRO-SKIN®. The reduction of E. coli on VITRO-SKIN® was similar to the log reduction obtained when washing human hands. The S. aureus count on a human hand was both calculated in different scenarios describing different contamination routes starting from a contaminated hand using the exposure assessment model, and measured on an experimental setup using VITRO-SKIN® for validation. A linear relationship was obtained between the analysed level of S. aureus and the calculated level. However, the calculated levels of S. aureus on the VITRO-SKIN® in the scenarios were 1–1.5 log lower than the analysed level. One of the scenarios was used to study the effect of interventions like hand washing and cleaning of surfaces.手卫生、清洁与消毒是医疗机构与食品行业卫生管理的前置必备条件。为助力风险管理工作，需对各类污染场景与干预措施开展评估。本研究通过人工皮肤实验体系，获取了金黄色葡萄球菌（Staphylococcus aureus）的转移率与消减数据。该实验方法可避免受试人员接触致病性细菌。研究构建并应用了一种暴露评估模型，用于评估不同污染途径与卫生干预措施的效果。通过印迹系列实验，计算得到接种了金黄色葡萄球菌的VITRO-SKIN®向物体表面（fomites）的细菌转移率。相较于物体表面，VITRO-SKIN®更易造成细菌播散。对不同表面实施清洁后，金黄色葡萄球菌的消减幅度介于<1至7 log CFU之间。无法得出某一特定试片材质、清洁剂、清洁湿巾、污染程度或湿度可始终导致金黄色葡萄球菌出现高或低幅度消减的结论。研究以人工皮肤VITRO-SKIN®为载体，评估了洗手过程中金黄色葡萄球菌与大肠杆菌（E. coli）的消减效果。VITRO-SKIN®上大肠杆菌的对数消减幅度，与人体手部洗手后的对数消减结果相近。研究通过暴露评估模型，针对以污染手部为起点的各类污染途径场景，计算了人体手部的金黄色葡萄球菌菌落数；同时借助VITRO-SKIN®构建实验体系开展实测，以验证计算结果。实测金黄色葡萄球菌菌落数与计算所得菌落数之间呈现线性相关关系。但在各场景中，VITRO-SKIN®上计算得到的金黄色葡萄球菌菌落数，较实测值低1~1.5 log。其中一个场景被用于研究洗手与表面清洁等干预措施的实施效果。