Shen Yun, Haig Sarah-Jane, Prussin Aaron J, LiPuma John J, Marr Linsey C, Raskin Lutgarde
Department of Civil and Environmental Engineering, University of Michigan, 1351 Beal Avenue, Ann Arbor, MI 48109, USA.
Department of Civil and Environmental Engineering, Virginia Tech, 418 Durham Hall, Blacksburg, VA 24061, USA.
PNAS Nexus. 2022 Nov 10;1(5):pgac145. doi: 10.1093/pnasnexus/pgac145. eCollection 2022 Nov.
Nontuberculous mycobacteria (NTM) are frequently present in municipal drinking water and building plumbing, and some are believed to cause respiratory tract infections through inhalation of NTM-containing aerosols generated during showering. However, the present understanding of NTM transfer from water to air is insufficient to develop NTM risk mitigation strategies. This study aimed to characterize the contribution of shower water to the abundance of viable NTM in indoor air. Shower water and indoor air samples were collected, and 16S rRNA and genes were sequenced. The sequencing results showed that running the shower impacted the bacterial community structure and NTM species composition in indoor air by transferring certain bacteria from water to air. A mass balance model combined with NTM quantification results revealed that on average 1/132 and 1/254 of NTM cells in water were transferred to air during 1 hour of showering using a rain and massage showerhead, respectively. A large fraction of the bacteria transferred from water to air were membrane-damaged, i.e. they had compromised membranes based on analysis by live/dead staining and flow cytometry. However, the damaged NTM in air were recoverable as shown by growth in a culture medium mimicking the respiratory secretions of people with cystic fibrosis, implying a potential infection risk by NTM introduced to indoor air during shower running. Among the recovered NTM, was the dominant species as determined by gene sequencing. Overall, this study lays the groundwork for future pathogen risk management and public health protection in the built environment.
非结核分枝杆菌（NTM）经常存在于市政饮用水和建筑管道中，一些人认为通过吸入淋浴时产生的含有NTM的气溶胶会导致呼吸道感染。然而，目前对NTM从水转移到空气的理解不足以制定NTM风险缓解策略。本研究旨在确定淋浴水对室内空气中存活NTM丰度的贡献。收集了淋浴水和室内空气样本，并对16S rRNA和基因进行了测序。测序结果表明，运行淋浴通过将某些细菌从水转移到空气，影响了室内空气中的细菌群落结构和NTM物种组成。结合NTM定量结果的质量平衡模型显示，使用雨淋式和按摩式淋浴喷头淋浴1小时期间，水中平均分别有1/132和1/254的NTM细胞转移到空气中。从水转移到空气的大部分细菌都有膜损伤，即根据活/死染色和流式细胞术分析，它们的膜受到了损害。然而，如在模拟囊性纤维化患者呼吸道分泌物的培养基中生长所示，空气中受损的NTM是可恢复的，这意味着淋浴运行期间引入室内空气中的NTM存在潜在感染风险。在回收的NTM中，通过基因测序确定为优势种。总体而言，本研究为未来建筑环境中的病原体风险管理和公共卫生保护奠定了基础。
