Salmonella spp

Salmonella are gram-negative, flagellated, facultative intracellular, anaerobic bacilli with O, H and Vi surface antigens. Once ingested, Salmonella survives the gastric acid barrier and penetrates the epithelial cells of the small and large intestines. The invasion of the epithelial cells stimulates the release of cytokines and a subsequent inflammatory response leading to diarrhea and possible ulceration of the mucosa.[NCBI Books: 8435] Antibodies to Salmonella are the body's defense when the bacteria is outside of its host cell which occurs at the initial infection and when the bacillus moves from cell to cell. There is a 10 minute window of opportunity when the Salmonella bacillus leaves the macrophage to invade another. During that time, antibodies and complement work to eradicate the bacilli, but some of the extracellular bacilli will evade attack and enter another host cell. Studies have shown that vaccines play an important role in the fight against typhoid fever