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Characterization of aerosols containing Legionella generated upon nebulization

View Article: PubMed Central - PubMed

ABSTRACT

Legionella pneumophila is, by far, the species most frequently associated with Legionnaires’ disease (LD). Human infection occurs almost exclusively by aerosol inhalation which places the bacteria in juxtaposition with alveolar macrophages. LD risk management is based on controlling water quality by applying standardized procedures. However, to gain a better understanding of the real risk of exposure, there is a need (i) to investigate under which conditions Legionella may be aerosolized and (ii) to quantify bacterial deposition into the respiratory tract upon nebulization. In this study, we used an original experimental set-up that enables the generation of aerosol particles containing L. pneumophila under various conditions. Using flow cytometry in combination with qPCR and culture, we determined (i) the size of the aerosols and (ii) the concentration of viable Legionella forms that may reach the thoracic region. We determined that the 0.26–2.5 μm aerosol size range represents 7% of initial bacterial suspension. Among the viable forms, 0.7% of initial viable bacterial suspension may reach the pulmonary alveoli. In conclusion, these deposition profiles can be used to standardize the size of inoculum injected in any type of respiratory tract model to obtain new insights into the dose response for LD.

No MeSH data available.


Experimental set-up for the generation and characterization of aerosols.
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f1: Experimental set-up for the generation and characterization of aerosols.

Mentions: Aerosol generation by an e-Base® vibrating-mesh nebulizer was performed in a glove box (Fig. 1). Briefly, the Legionella-calibrated suspension was introduced into the nebulizer reservoir. The nebulizer was connected to the low-pressure impactor (DLPI) by an artificial throat. A pump-simulating inspiration was used during nebulization to collect aerosols on the 13-DLPI stages. The size classification in DLPI was set at up to 10 μm, with evenly distributed impactor stages.


Characterization of aerosols containing Legionella generated upon nebulization
Experimental set-up for the generation and characterization of aerosols.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037422&req=5

f1: Experimental set-up for the generation and characterization of aerosols.
Mentions: Aerosol generation by an e-Base® vibrating-mesh nebulizer was performed in a glove box (Fig. 1). Briefly, the Legionella-calibrated suspension was introduced into the nebulizer reservoir. The nebulizer was connected to the low-pressure impactor (DLPI) by an artificial throat. A pump-simulating inspiration was used during nebulization to collect aerosols on the 13-DLPI stages. The size classification in DLPI was set at up to 10 μm, with evenly distributed impactor stages.

View Article: PubMed Central - PubMed

ABSTRACT

Legionella pneumophila is, by far, the species most frequently associated with Legionnaires’ disease (LD). Human infection occurs almost exclusively by aerosol inhalation which places the bacteria in juxtaposition with alveolar macrophages. LD risk management is based on controlling water quality by applying standardized procedures. However, to gain a better understanding of the real risk of exposure, there is a need (i) to investigate under which conditions Legionella may be aerosolized and (ii) to quantify bacterial deposition into the respiratory tract upon nebulization. In this study, we used an original experimental set-up that enables the generation of aerosol particles containing L. pneumophila under various conditions. Using flow cytometry in combination with qPCR and culture, we determined (i) the size of the aerosols and (ii) the concentration of viable Legionella forms that may reach the thoracic region. We determined that the 0.26–2.5 μm aerosol size range represents 7% of initial bacterial suspension. Among the viable forms, 0.7% of initial viable bacterial suspension may reach the pulmonary alveoli. In conclusion, these deposition profiles can be used to standardize the size of inoculum injected in any type of respiratory tract model to obtain new insights into the dose response for LD.

No MeSH data available.