Desiccation tolerance as a driver of environmental persistence and transmission in nosocomial bacterial pathogens.

Hospital-acquired infections (HAIs) represent a major global health burden, leading to increased patient morbidity, mortality, and healthcare costs. These infections frequently occur following patient contact with microbial pathogens persisting on indwelling devices and other abiotic surfaces in the hospital environment. A key driver of this persistence is the ability to survive the total loss of water, a phenomenon known as desiccation tolerance. While desiccation tolerance has been studied across various kingdoms of life, comparatively little is known about the molecular mechanisms that enable bacterial pathogens to tolerate extreme water loss. In this review, we will examine the consequences of desiccation stress in bacteria and highlight conserved mechanisms by which bacterial cells tolerate drying, including spore formation, capsule synthesis, osmolyte accumulation, expression of intrinsically disordered proteins, and other protective mechanisms. We will also examine the mechanisms and consequences of desiccation tolerance in several clinically significant nosocomial pathogens and review emerging evidence that desiccation stress responses may influence other bacterial traits, such as antimicrobial resistance, polymicrobial community interactions, and virulence. Understanding the mechanisms by which nosocomial pathogens tolerate desiccation may reveal novel strategies to disrupt pathogen reservoirs and reduce future HAI transmission.