Mendes Marta, Andrade Oliveira Ana, Pires Olga, Branca Fernando, Beirão Maria, Santa-Cruz André, Carvalho Alexandre, Alves Joana
Department of Internal Medicine. Hospital of Braga. Braga. Portugal.
Department of Molecular Biology. Hospital of Braga. Braga. Portugal.
Acta Med Port. 2021 Dec 2;34(12):851-856. doi: 10.20344/amp.16215. Epub 2021 May 20.
Transmission of COVID-19 through close contact and droplets is well established, but the influence of aerosol and surface contamination remains to be determined. Literature is scarce and inconsistent about the viable virus particles free-distance from infected patients, as well as about different swabbing methods for surface contamination evaluation. The aim of this study was to evaluate the most sensitive method for the assessment of surface contamination, classify the likelihood of environmental contamination in risk zones and compare the environmental contamination between oxygenation and ventilatory support.
Swabs from potentially contaminated surfaces in a COVID-19 ward, with patients treated with different types of oxygen and ventilatory support, were collected. Three types of swabs were compared in order to evaluate the most sensitive collection method. For risk zone categorization, areas were divided according to the distance from the patient.
Of the 63 swabs collected, 17 (27%) tested positive for the presence of SARS-CoV-2. The highest positivity rate was observed with the sterile premoistened swab with saline (n = 8; 38%), but without statistically significant differences. The highest number of positive samples were collected from the high-risk zones, specifically those located one meter from the patient (n = 13; 48%), with statistically significant differences. Only the rooms of patients supported with non-invasive ventilation or high-flow nasal cannula had evidence of bedroom contamination, with 45% and 27% of swab positivity, with statistically significant differences.
Our findings favour the premoistened swab without transport medium for surface contamination assessment, even though without statistical differences. A statistically significant trend supporting the division in risk zones, according to the distance from the patient, was also identified. The higher positivity rate from the non-invasive ventilation and high-flow nasal cannula bedrooms suggests a significant association between ventilatory strategies and surface contamination, probably due to higher particle dispersion.
Our findings support the use of the sterile premoistened swab without preservation medium, the classification of risk areas considering the distance from the patient, and the variability of RNA dispersion between oxygenation and ventilatory support.
新型冠状病毒肺炎（COVID-19）通过密切接触和飞沫传播已得到充分证实，但气溶胶和表面污染的影响仍有待确定。关于感染患者周围存活病毒颗粒的自由传播距离以及用于评估表面污染的不同拭子采样方法的文献稀少且不一致。本研究的目的是评估评估表面污染的最敏感方法，对风险区域的环境污染可能性进行分类，并比较氧疗和通气支持情况下的环境污染情况。
收集了COVID-19病房中接受不同类型氧疗和通气支持的患者周围潜在污染表面的拭子。比较了三种拭子类型，以评估最敏感的采集方法。为了进行风险区域分类，根据与患者的距离对区域进行划分。
在收集的63份拭子中，17份（27%）检测出严重急性呼吸综合征冠状病毒2（SARS-CoV-2）呈阳性。使用无菌预湿盐水拭子观察到的阳性率最高（n = 8；38%），但无统计学显著差异。阳性样本数量最多的是从高风险区域采集的，特别是距离患者一米处的区域（n = 13；48%），具有统计学显著差异。只有接受无创通气或高流量鼻导管支持的患者房间有卧室污染的证据，拭子阳性率分别为45%和27%，具有统计学显著差异。
我们的研究结果支持使用无运输培养基的预湿拭子进行表面污染评估，尽管无统计学差异。还发现了一个具有统计学意义的趋势，支持根据与患者的距离划分风险区域。无创通气和高流量鼻导管卧室的较高阳性率表明通气策略与表面污染之间存在显著关联，可能是由于更高的颗粒扩散。
我们的研究结果支持使用无保存培养基的无菌预湿拭子；考虑与患者的距离对风险区域进行分类；以及氧疗和通气支持之间RNA扩散的变异性。
