Stress-induced adaptations in Salmonella: A ground for shaping its pathogenesis

Microorganisms are able to adapt to multiple adverse environmental conditions that facilitate their survival. These microorganisms including bacteria, viruses, algae, fungi, and protozoans are exposed to different abiotic and biotic challenges throughout their life. Adaptations help these organisms to overcome the challenges and evolve as successful pathogens which at the same time might lead to severe disease outcome. The intracellular gram-negative pathogen Salmonella, the causative agent of typhoid fever has evolved into a successful pathogen and shows increasing host mortality and morbidity every year across the globe. Salmonella adapts itself in the different extreme host and non-host environments both at genetic and phenotypic level leading to their better survival and propagation. The uncontrolled and improper use of antibiotics against several Salmonella serovars has not only given rise to various multidrug resistance strains but also the emergence of hyper-infectious Salmonella strains adds to the severity of disease manifestation and treatment. Besides, several disadvantages in the existing Salmonella vaccines stand against the current therapeutic interventions against the bug. This review deals with the wide array of stresses that Salmonella encounter in its life cycle and outlines the adaptations occurring in Salmonella upon exposure to such stresses as well as how adaptations help the pathogen to withstand such extreme conditions. Insights in these aspects will help to understand Salmonella pathogenesis and associated consequences which might help in the development of new strategies in combating Salmonella infection.