The mechanism underlying Legionella aerosolization and entry into the respiratory tract remains poorly documented. In previous studies, we characterized the aerodynamic behaviour of Legionella aerosols and assessed their regional deposition within the respiratory tract using a human-like anatomical model. The aim of this study was to assess whether this experimental setup could mimic the exposure to bioaerosols generated by showers. To achieve this objective we performed experiments to measure the mass median aerodynamic diameter (MMAD) as well as the emitted dose and the physiological state of the airborne bacteria generated by a shower and two nebulizers (vibrating-mesh and jet nebulizers). The MMADs of the dispersed bioaerosols were characterized using a 12-stage cascade low-pressure impactor. The amount of dispersed airborne bacteria from a shower was quantified using a Coriolis® Delta air sampler and compared to the airborne bacteria reaching the thoracic region in the experimental setup. The physiological state and concentration of airborne Legionella were assessed by qPCR for total cells, culture for viable and cultivable Legionella (VC), and flow cytometry for viable but non-cultivable Legionella (VBNC). In summary, the experimental setup developed appears to mimic the bioaerosol emission of a shower in terms of aerodynamic size distribution. Compared to the specific case of a shower used as a reference in this study, the experimental setup developed underestimates by 2 times (when the jet nebulizer is used) or overestimates by 43 times (when the vibrating-mesh nebulizer is used) the total emitted dose of airborne bacteria. To our knowledge, this report is the first showing that an experimental model mimics so closely an exposure to Legionella aerosols produced by showers to assess human lung deposition and infection in well-controlled and safe conditions.

军团菌雾化和进入呼吸道的潜在机制仍然文献不足。在以前的研究中，我们表征了军团菌的空气动力学行为气溶胶，并使用类似人体的解剖模型评估其在呼吸道内的局部沉积。这项研究的目的是评估该实验装置是否可以模拟淋浴产生的生物气溶胶的暴露。为了实现此目标，我们进行了实验，以测量质量平均空气动力学直径（MMAD）以及由淋浴器和两个雾化器（振动网和喷射雾化器）产生的空气传播细菌的发射剂量和生理状态。分散的生物气溶胶的MMADs使用12级级联低压冲击器进行表征。使用Coriolis®Delta空气采样器量化了淋浴后分散的空气传播细菌的数量，并与实验设置中到达胸腔区域的空气传播细菌进行了比较。通过qPCR评估军团菌的总细胞数，培养可行和可培养的军团菌（VC），流式细胞仪评估可行但不可培养的军团菌（VBNC）。总而言之，开发的实验装置似乎在空气动力学尺寸分布方面模仿了淋浴的生物气溶胶排放。与本研究中作为参考的淋浴的特定情况相比，实验装置开发的总排放量低估了2倍（使用喷射雾化器时）或高估了43倍（使用振动筛网雾化器时）空气中细菌的剂量。据我们所知，该报告是第一个表明实验模型非常接近军团菌暴露的报告。 淋浴产生的浮质可用来评估人的肺部沉积和感染情况，控制良好且安全。