Evaporating droplet dynamics enhances bacterial pathogenesis on fomites*

The current study provides first of its kind insights into the complete lifecycle of fomite-mediated bacterial pathogenesis in evaporating droplets of both neutral and nutrient-rich media. The remnant bacterial precipitate post evaporation of the host liquid medium contaminates the surfaces (identified as fomites), and further aggravates disease transmission.Salmonella Typhimurium (STM), being the most virulent gut pathogen, found in contaminated food and water [1] is used for experimental purposes. Investigation of the dried STM laden droplets reveal distinct bacterial agglomeration patterns, governed by the flow dynamics and the nutrient scale of the host mediums. The residual STM, overwhelmed by depletion of moisture and flow stress, exhibit reduced viability. However, their hyper-proliferating responses, confirmed from macrophages and in vivo animal (mice) experiments signify augmented infection potential of fomites. This study demonstrates that dried bacterial morphologies (formed within minutes) on organic and inorganic surfaces, significantly contribute to enhanced pathogenesis of fomites that can last up to several days.