Spatiotemporal evaporating droplet dynamics on fomites enhances long term bacterial pathogenesis

Majee, Sreeparna; Chowdhury, Atish Roy; Pinto, Roven; Chattopadhyay, Ankur; Agharkar, Amey Nitin; Chakravortty, Dipshikha; Basu, Saptarshi

doi:10.1038/s42003-021-02711-z

Cited by 27 publications

(33 citation statements)

References 71 publications

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“…Earlier, we reported that irrespective of the presence of nutrients, the in vitro viability of wild-type Salmonella inside the sessile droplets is severely compromised post-evaporation. Moreover, the bacteria recovered from dried nutrient-rich sessile droplets hyper-proliferates inside the RAW264.7 macrophages 17 . However, the in vitro viability of bacteria retrieved from the impacted dried droplets on solid surfaces with specific velocities has not been tested before.…”

Section: (G)mentioning

confidence: 98%

Section: Fig1mentioning

confidence: 98%

“…Aerosolized Salmonella can colonize in the ceca, trachea, liver, and spleen of poultry broilers 16 . Despite their poor in vitro survival due to evaporation stress Salmonella Typhimurium (STM) retrieved from inanimate surfaces showed hyper-virulence in RAW264.7 cells 17 . These aspects add to the importance of studying the effect of Salmonella -laden drops for various impact velocities and base fluid mediums (nutrient-rich or neutral) to understand the transmission risk.…”

Section: Fig1mentioning

confidence: 99%

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Physiological Characteristics of Bacterial Droplets Indicate a Catastrophic Consequence With an Increase in Impact Velocity

Hariharan

Chowdhury

Sandepudi

et al. 2022

Preprint

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Droplet impacts on various surfaces play a profound role in different bio-physiological processes and engineering applications. The current study opens a new realm that investigates the plausible effect of impact velocities on bacteria-laden droplets against a solid surface. We unveiled the alarming consequences of Salmonella Typhimurium (STM) laden drop, carrying out the in vitro and intracellular viability of STM to the impact Weber numbers ranging from 100-750. The specified Weber number range mimics the velocity range occurring during the respiratory processes, especially the airborne dispersion of drops during cough. A thick ring of bacterial deposition was observed in all cases irrespective of impacting velocity and the nutrient content of the bacterial medium. The mechanical properties of the bacterial deposit examined using Atomic Force Microscopy reveals the deformation of bacterial morphology, cushioning effect and adhesion energy to determine the cell-cell interactions. The impact velocity induces the shear stress onto the cell walls of STM, thereby deteriorating the in vitro viability. However, we found that even with compromised in vitro viability, Salmonella retrieved from deposited patterns impacted at higher velocity revealed an increased expression of phoP (the response regulator of the PhopQ two-component system) and uninterrupted intracellular proliferation in macrophages. The inability of STM ΔphoP growth in nutrient-rich dried droplets to the subjected impact velocities signifies the predominant role of phoP in maintaining the virulence of Salmonella during desiccation stress. Our findings open a promising avenue for understating the effect of bacteria-laden drop impact and its role in disease spread.Abstract Figure

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Section: (G)mentioning

confidence: 98%

Section: Fig1mentioning

confidence: 98%

Section: Fig1mentioning

confidence: 99%

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Physiological Characteristics of Bacterial Droplets Indicate a Catastrophic Consequence With an Increase in Impact Velocity

Hariharan

Chowdhury

Sandepudi

et al. 2022

Preprint

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“…We concluded that in Salmonella Typhimurium, OmpA serves dual functions to protect the bacteria from phagocytosis and then help in its survival within macrophages. After entering the host cell, Salmonella resides within a modified phagosomal compartment called Salmonella containing vacuole (SCV) [ 18 ]. The intracellular life and proliferation of Salmonella depend on the stability and integrity of SCV.…”

Section: Resultsmentioning

confidence: 99%

Salmonella Typhimurium outer membrane protein A (OmpA) renders protection from nitrosative stress of macrophages by maintaining the stability of bacterial outer membrane

et al. 2022

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Bacterial porins are highly conserved outer membrane proteins used in the selective transport of charged molecules across the membrane. In addition to their significant contributions to the pathogenesis of Gram-negative bacteria, their role(s) in salmonellosis remains elusive. In this study, we investigated the role of outer membrane protein A (OmpA), one of the major outer membrane porins of Salmonella, in the pathogenesis of Salmonella Typhimurium (STM). Our study revealed that OmpA plays an important role in the intracellular virulence of Salmonella. An ompA deficient strain of Salmonella (STM ΔompA) showed compromised proliferation in macrophages. We found that the SPI-2 encoded virulence factors such as sifA and ssaV are downregulated in STM ΔompA. The poor colocalization of STM ΔompA with LAMP-1 showed that disruption of SCV facilitated its release into the cytosol of macrophages, where it was assaulted by reactive nitrogen intermediates (RNI). The enhanced recruitment of nitrotyrosine on the cytosolic population of STM ΔompAΔsifA and ΔompAΔssaV compared to STM ΔsifA and ΔssaV showed an additional role of OmpA in protecting the bacteria from host nitrosative stress. Further, we showed that the generation of greater redox burst could be responsible for enhanced sensitivity of STM ΔompA to the nitrosative stress. The expression of several other outer membrane porins such as ompC, ompD, and ompF was upregulated in STM ΔompA. We found that in the absence of ompA, the enhanced expression of ompF increased the outer membrane porosity of Salmonella and made it susceptible to in vitro and in vivo nitrosative stress. Our study illustrates a novel mechanism for the strategic utilization of OmpA by Salmonella to protect itself from the nitrosative stress of macrophages.

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“…In the case of disease transmission, evaporation affects the physiochemical environment inside the microdroplets, for example, osmolality and confinement. These changes affect the metabolism, physiology, and biological activity of the pathogens. − The self-secreted secondary metabolites of the microorganisms that stay within the droplets add to the complexity.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic Droplet Cluster with Distributed Evaporation Rates as a Model for Bioaerosols

et al. 2022

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Aerosols and microdroplets are known to act as carriers for pathogens or vessels for chemical reactions. The natural occurrence of evaporation of these droplets has implications for the viability of pathogens or chemical processes. For example, it is important to understand how pathogens survive extreme physiochemical conditions such as confinement and osmotic stress induced by evaporation of aerosol droplets. Previously, larger evaporating droplets were proposed as model systems as the processes in the tiny aerosol droplets are difficult to image. In this context, we propose the concept of evaporation of capillary-clustered aqueous microdroplets dispersed in a thin oil layer. The configuration produces spatially segregated evaporation rates. It allows comparing the consequences of evaporation and its rate for processes occurring in droplets. As a proof of concept, we study the consequences of evaporation and its rate using Escherichia coli (E. coli) and Bacillus subtilis as model organisms. Our experiments indicate that the rate of evaporation of microdroplets is an important parameter in deciding the viability of contained microorganisms. With slow evaporation, E. coli could mitigate the osmotic stress by K + ion uptake. Our method may also be applicable to other evaporating droplet systems, for example, microdroplet chemistry to understand the implications of evaporation rates.

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Spatiotemporal evaporating droplet dynamics on fomites enhances long term bacterial pathogenesis

Cited by 27 publications

References 71 publications

Physiological Characteristics of Bacterial Droplets Indicate a Catastrophic Consequence With an Increase in Impact Velocity

Physiological Characteristics of Bacterial Droplets Indicate a Catastrophic Consequence With an Increase in Impact Velocity

Salmonella Typhimurium outer membrane protein A (OmpA) renders protection from nitrosative stress of macrophages by maintaining the stability of bacterial outer membrane

Microfluidic Droplet Cluster with Distributed Evaporation Rates as a Model for Bioaerosols

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