Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis 55455, Minnesota, United States.
Norwegian University of Science and Technology, Trondheim 7031, Norway.
Environ Sci Technol. 2020 Dec 15;54(24):15914-15924. doi: 10.1021/acs.est.0c06357. Epub 2020 Nov 24.
There is concern about potential exposure to opportunistic pathogens when reopening buildings closed due to the COVID-19 pandemic. In this study, water samples were collected before, during, and after flushing showers in five unoccupied (i.e., for ∼2 months) university buildings with quantification of opportunists via a cultivation-based assay ( only) and quantitative PCR. were not detected by either method; spp., nontuberculous mycobacteria (NTM), and complex (MAC), however, were widespread. Using quantitative microbial risk assessment (QMRA), the estimated risks of illness from exposure to and MAC via showering were generally low (i.e., less than a 10 daily risk threshold), with the exception of systemic infection risk from MAC exposure in some buildings. Flushing rapidly restored the total chlorine (as chloramine) residual and decreased bacterial gene targets to building inlet concentrations within 30 min. During the postflush stagnation period, the residual chlorine dissipated within a few days and bacteria rebounded, approaching preflush concentrations after 6-7 days. These results suggest that flushing can quickly improve water quality in unoccupied buildings, but the improvement may only last a few days.
人们担心在因 COVID-19 大流行而关闭的建筑物重新开放时，可能会接触到机会性病原体。在这项研究中，在五个无人居住的（即约 2 个月）大学校舍中，在冲洗淋浴之前、期间和之后收集水样，通过基于培养的测定法（仅）和定量 PCR 对机会性病原体进行定量。未通过任何一种方法检测到 ；然而， spp.、非结核分枝杆菌（NTM）和 复合体（MAC）则广泛存在。使用定量微生物风险评估（QMRA），从淋浴接触 和 MAC 而患病的估计风险通常较低（即低于每日 10 风险阈值），除了一些建筑物中 MAC 暴露引起的全身性感染风险。冲洗可在 30 分钟内迅速恢复总氯（作为氯胺）残留，并将细菌基因靶标降低至建筑物入口浓度。在冲洗后的停滞期内，余氯在几天内消散，细菌反弹，在 6-7 天后达到冲洗前的浓度。这些结果表明，冲洗可以迅速改善无人居住建筑物中的水质，但改善可能只能持续几天。
