An experimental study on the effect of respiratory fluid composition on bacterial viability and deposit adhesion characteristics*

This study investigates the impact of respiratory fluid composition on the viability of pathogens and the adhesive properties of deposits formed when the surrogate respiratory fluid droplets dry on surfaces. Given the potential threat of respiratory fluid-containing pathogens to human health, understanding the conditions under which deposits form and the state of the pathogens within them is crucial. Clinical research has shown that salt ions and mucin are the primary components of respiratory fluid, which can vary significantly depending on the individual's pathological conditions. The study demonstrates that variations in salt and mucin content in respiratory droplets have a significant effect on the viability of pathogens and the adhesive properties of the deposits. To understand the underlying factors influencing viability and adhesion, the researchers examine the dynamics of evaporation, internal flow, and precipitation. Additionally, the characteristics of the deposits are analyzed using optical profilometry, scanning electron microscopy, and atomic force microscopy, while pathogen distribution is investigated using confocal microscopy.