Characterization of aerosols containing Legionella generated upon nebulization

Allegra, Séverine; Leclerc, Lara; Massard, Pierre André; Girardot, Françoise; Riffard, Serge; Pourchez, Jérémie

doi:10.1038/srep33998

Cited by 47 publications

(39 citation statements)

References 41 publications

(57 reference statements)

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“…All BCYE plates were observed under UV at 366 nm to identify and enumerate Legionella colonies (CFU) expressing GFP. For qPCR, the quantification was made as described in our previous study (Allegra et al, 2016). Briefly, after a centrifugation at 8000 rpm for 10 min of a 1 mL sample (initial bacterial suspension or BALF), plasmid DNA was extracted (NuCleoSpin Plasmid kit, Macherey-Nagel).…”

Section: Broncho-alveolar Lavage Fluids Analysismentioning

confidence: 99%

“…Aerosols containing Legionella generated upon nebulization were previously extensively characterized (Allegra et al, 2016). It was determined that the distribution of airborne Legionella showed a Mass Median Aerodynamic Diameter (MMAD) of 3.4 ± 0.4 µm with a Geometric Standard Deviation (GSD) of 4.1 ± 1.2 µm.…”

Section: Aerodynamic Characterization Of the Legionella Bioaerosolmentioning

confidence: 99%

“…Lungs were ventilated by passive expansion as in human physiological ventilation allowing to reproduce inhalation exposure to aerosols (El Merhie et al, 2016;Le Guellec et al, 2014;Leclerc et al, 2014a;Perinel et al, 2016Perinel et al, , 2017. Previously, characterized Legionella aerosols generated upon nebulization using a fluorescent Legionella strain (Allegra et al, 2016). This strain was aerosolized in the chimeric model as ventilation was ongoing and then visualized using the Cellvizio  Lab technology (probe-based confocal fluorescence microscope).…”

Section: Introductionmentioning

confidence: 99%

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Deposition pattern of aerosolized Legionella using an ex vivo human-porcine respiratory model

Périnel

Forest

Landraud

et al. 2018

International Journal of Hygiene and Environmental Health

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Legionella are bacteria responsible for severe lung pathologies. However how they enter and are deposited within the respiratory tract remains poorly documented. Data using animal testing led to the establishment of mathematical models allowing the estimation of aerosol dispersion risks. But direct extrapolation to humans is questionable and experimental models more physiologically representative of the inhalation route are welcome. The aim of this study was to develop a model as close as possible to the human anatomy and physiology allowing determining the deposition pattern of aerosolized Legionella while limiting in vivo experiments. To that purpose, we adapted the chimeric respiratory tract model we previously developed. This original model consisted of a replica of the human upper respiratory airways made by additive manufacturing connected to ex vivo porcine lungs ventilated by passive expansion, as for humans in physiological conditions. These experiments didn't imply specific animal sacrifices as pigs were bred for human consumption and lungs were considered as wastes by the slaughterhouse. Fluorescent Legionella were aerosolized and visualized using Cellvizio Lab (probe-based confocal fluorescence microscope). Legionella were found in the whole respiratory tract. Broncho-alveolar lavages were also performed and the amount of Legionella reaching the thoracic region was quantified by culture and qPCR. Legionella were found preferentially in the left upper lobe compared to the right lower lobe. To our knowledge, it is the first time that experiments mimicking so closely human exposure by inhalation are performed while limiting animal experiments and providing a model for further Legionella infectious risk assessment.

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Section: Broncho-alveolar Lavage Fluids Analysismentioning

confidence: 99%

Section: Aerodynamic Characterization Of the Legionella Bioaerosolmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Deposition pattern of aerosolized Legionella using an ex vivo human-porcine respiratory model

Périnel

Forest

Landraud

et al. 2018

International Journal of Hygiene and Environmental Health

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“…The physiological states of the airborne Legionella collected in the thoracic region (TR) were quantified by flow cytometry assays (FCAs) as previously described (Allegra et al, 2016(Allegra et al, , 2008.…”

Section: Description Of the "Real" Shower Experiments Used As A Refermentioning

confidence: 99%

“…In previous works, we used a medical nebulization device to generate Legionella aerosols. Thus, we extensively characterized the bioaerosols produced by a vibrating-mesh nebulizer in terms of aerodynamic features and airborne Legionella emitted dose (Allegra et al 2016). We also experimentally assessed the deposition of these bacteria in the pulmonary region using a 3D replica of the upper airways (Pourchez et al, 2017) and using an ex vivo ventilated porcine lung as an innovative human-like respiratory model (Perinel et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

A valuable experimental setup to model exposure to Legionella’s aerosols generated by shower-like systems

et al. 2020

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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 noncultivable 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.

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Sensors and Analytical Technologies for Air Quality: Particulate Matters and Bioaerosols

Sutarlie

Loh

2020

Chemistry An Asian Journal

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Particulate matters (PMs), e. g. dusts, fibres, smokes, fumes, mists, liquid droplets and airborne respirable solid or liquid particles, are the major sources of air pollution concerning outdoor and indoor air quality. Among various PMs, bioaerosols are airborne particles that are either living organisms (bacteria, viruses, and fungi) or originate from living organisms (endotoxin, allergen, etc). PMs and/or bioaerosols have adverse health effects of infection, allergy, and irritation. Proper management and source identification of PMs and bioaerosols will reduce their negative health impact. In this review, we will discuss the analytical technologies and sensors for PMs and bioaerosols. We will first introduce four types of PM analysers, namely, filter-based gravimetric method (GMM), optical method, β-ray absorption method (BAM), and tapered element oscillating microbalance (TEOM). We will provide examples of how commercial PM analyzers of different principles have been compared and calibrated for specific applications under different climate conditions of specific geographic locations. For bioaerosols, having more complex biological and biochemical identity, we will start from air sampling techniques, followed by a discussion of various detection methods (plate culture, molecular methods, immunoassays and biosensors) in association with compatible sampling technologies. Using Influenza A (H1 N1) virus and SARS-CoV-2 (COVID-19) virus as examples, we have highlighted air sampling and detection challenges for viral aerosols relative to bacterial and fungal aerosols. Finally, we provide a perspective for future trends according to the limitation of current commercial products and the key challenges in this field.

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Characterization of aerosols containing Legionella generated upon nebulization

Cited by 47 publications

References 41 publications

Deposition pattern of aerosolized Legionella using an ex vivo human-porcine respiratory model

Deposition pattern of aerosolized Legionella using an ex vivo human-porcine respiratory model

A valuable experimental setup to model exposure to Legionella’s aerosols generated by shower-like systems

Sensors and Analytical Technologies for Air Quality: Particulate Matters and Bioaerosols

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