An assessment of the airborne longevity of group A Streptococcus

Henry P Oswin; Evie Blake; Allen E Haddrell; Adam H R Finn; Shiranee Sriskandan; Jonathan P Reid; Alice Halliday; Anu Goenka

doi:10.1099/mic.0.001421

An assessment of the airborne longevity of group A Streptococcus

Henry P Oswin, Evie Blake, Allen E Haddrell, Adam H R Finn, Shiranee Sriskandan, Jonathan P Reid, Alice Halliday^*, Anu Goenka^*

^*Corresponding author for this work

Research output: Contribution to journal › Article (Academic Journal) › peer-review

5 Citations (Scopus)

Abstract

Group A streptococcus (GAS) infections result in more than 500 000 deaths annually. Despite mounting evidence for airborne transmission of GAS, little is known about its stability in aerosol. Measurements of GAS airborne stability were carried out using the Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate (CELEBS) instrument. CELEBS measurements with two different isolates of GAS suggest that it is aerostable, with approximately 70 % of bacteria remaining viable after 20 min of levitation at 50 % relative humidity (RH), with lower survival as RH was reduced. GAS airborne viability loss was driven primarily by desiccation and efflorescence (i.e. salt crystallization), with high pH also potentially playing a role, given reduced survival in bicarbonate containing droplet compositions. At low enough RH for efflorescence to occur, a greater proportion of organic components in the droplet appeared to protect the bacteria from efflorescence. These first insights into the aerosol stability of GAS indicate that airborne transmission of these respiratory tract bacteria may occur, and that both the composition of the droplet containing the bacteria, and the RH of the air affect the duration of bacterial survival in this environment. Future studies will explore a broader range of droplet and air compositions and include a larger selection of GAS strains.

Original language	English
Article number	001421
Journal	Microbiology
Volume	170
Issue number	1
DOIs	https://doi.org/10.1099/mic.0.001421
Publication status	Published - 5 Jan 2024

Bibliographical note

Funding Information:
The authors would like to thank Liz Oliver for growing up the bacterial strains. SS also acknowledges the support of the Imperial College London NIHR Biomedical Research Centre.

Funding Information:
This work was funded by a Small Grant Award from the European Society of Paediatric Infectious Diseases (A.H./A.G.). A.H. acknowledges support from the Elizabeth Blackwell Institute, funded in part by the Wellcome Trust (grant number 204813/Z/16/Z). H.O. acknowledges support from the Engineering and Physical Sciences Research Council and the Defence Science and Technology Laboratory.

Publisher Copyright:
© 2024 The Authors.

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Physical & Theoretical

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title = "An assessment of the airborne longevity of group A Streptococcus",

abstract = "Group A streptococcus (GAS) infections result in more than 500 000 deaths annually. Despite mounting evidence for airborne transmission of GAS, little is known about its stability in aerosol. Measurements of GAS airborne stability were carried out using the Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate (CELEBS) instrument. CELEBS measurements with two different isolates of GAS suggest that it is aerostable, with approximately 70 \% of bacteria remaining viable after 20 min of levitation at 50 \% relative humidity (RH), with lower survival as RH was reduced. GAS airborne viability loss was driven primarily by desiccation and efflorescence (i.e. salt crystallization), with high pH also potentially playing a role, given reduced survival in bicarbonate containing droplet compositions. At low enough RH for efflorescence to occur, a greater proportion of organic components in the droplet appeared to protect the bacteria from efflorescence. These first insights into the aerosol stability of GAS indicate that airborne transmission of these respiratory tract bacteria may occur, and that both the composition of the droplet containing the bacteria, and the RH of the air affect the duration of bacterial survival in this environment. Future studies will explore a broader range of droplet and air compositions and include a larger selection of GAS strains.",

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note = "Funding Information: The authors would like to thank Liz Oliver for growing up the bacterial strains. SS also acknowledges the support of the Imperial College London NIHR Biomedical Research Centre. Funding Information: This work was funded by a Small Grant Award from the European Society of Paediatric Infectious Diseases (A.H./A.G.). A.H. acknowledges support from the Elizabeth Blackwell Institute, funded in part by the Wellcome Trust (grant number 204813/Z/16/Z). H.O. acknowledges support from the Engineering and Physical Sciences Research Council and the Defence Science and Technology Laboratory. Publisher Copyright: {\textcopyright} 2024 The Authors.",

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AU - Reid, Jonathan P

AU - Halliday, Alice

AU - Goenka, Anu

N1 - Funding Information: The authors would like to thank Liz Oliver for growing up the bacterial strains. SS also acknowledges the support of the Imperial College London NIHR Biomedical Research Centre. Funding Information: This work was funded by a Small Grant Award from the European Society of Paediatric Infectious Diseases (A.H./A.G.). A.H. acknowledges support from the Elizabeth Blackwell Institute, funded in part by the Wellcome Trust (grant number 204813/Z/16/Z). H.O. acknowledges support from the Engineering and Physical Sciences Research Council and the Defence Science and Technology Laboratory. Publisher Copyright: © 2024 The Authors.

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N2 - Group A streptococcus (GAS) infections result in more than 500 000 deaths annually. Despite mounting evidence for airborne transmission of GAS, little is known about its stability in aerosol. Measurements of GAS airborne stability were carried out using the Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate (CELEBS) instrument. CELEBS measurements with two different isolates of GAS suggest that it is aerostable, with approximately 70 % of bacteria remaining viable after 20 min of levitation at 50 % relative humidity (RH), with lower survival as RH was reduced. GAS airborne viability loss was driven primarily by desiccation and efflorescence (i.e. salt crystallization), with high pH also potentially playing a role, given reduced survival in bicarbonate containing droplet compositions. At low enough RH for efflorescence to occur, a greater proportion of organic components in the droplet appeared to protect the bacteria from efflorescence. These first insights into the aerosol stability of GAS indicate that airborne transmission of these respiratory tract bacteria may occur, and that both the composition of the droplet containing the bacteria, and the RH of the air affect the duration of bacterial survival in this environment. Future studies will explore a broader range of droplet and air compositions and include a larger selection of GAS strains.

AB - Group A streptococcus (GAS) infections result in more than 500 000 deaths annually. Despite mounting evidence for airborne transmission of GAS, little is known about its stability in aerosol. Measurements of GAS airborne stability were carried out using the Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate (CELEBS) instrument. CELEBS measurements with two different isolates of GAS suggest that it is aerostable, with approximately 70 % of bacteria remaining viable after 20 min of levitation at 50 % relative humidity (RH), with lower survival as RH was reduced. GAS airborne viability loss was driven primarily by desiccation and efflorescence (i.e. salt crystallization), with high pH also potentially playing a role, given reduced survival in bicarbonate containing droplet compositions. At low enough RH for efflorescence to occur, a greater proportion of organic components in the droplet appeared to protect the bacteria from efflorescence. These first insights into the aerosol stability of GAS indicate that airborne transmission of these respiratory tract bacteria may occur, and that both the composition of the droplet containing the bacteria, and the RH of the air affect the duration of bacterial survival in this environment. Future studies will explore a broader range of droplet and air compositions and include a larger selection of GAS strains.

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DO - 10.1099/mic.0.001421

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An assessment of the airborne longevity of group A Streptococcus

Abstract

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