Resumen de Stress Response in Listeria monocytogenes
Listeria monocytogenes is a food-borne pathogen widespread in the environment. The majority of human listeriosis is associated with consumption of contaminated food. It has the ability to invade many types of nonphagocytic cells and spread from cell to cell, crossing important barriers in host organism. Despite intensified surveillance in food manufacturing serious cases of listeriosis are still reported. Before L. monocytogenes causes disease it has to endure adverse conditions encountered in food during its processing and storage, such as supraoptimal temperatures, low pH, high osmolarity, presence of oxidants. In the human intestinal tract L. monocytogenes must overcome another set of challenges as the low pH of the stomach, volatile fatty acids, low oxygen levels, osmotic stress, nutrient variability, bile stress and natural flora in the intestine. To survive in hostile environment bacteria adjust their metabolism which involves expression of stress response genes. Consequently, bacteria synthesize proteins that repair damages, maintain the cell stability, eliminate the stress factor, and restore homeostasis. The stress response not only affects L. monocytogenes resistance to subsequent doses of stress factors, but can also alter the pathogen's virulence.
