What is the pathophysiology of Salmonella typhi (S typhi) infection?

Updated: Aug 19, 2019
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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Typhoidal salmonella co-opt the macrophages' cellular machinery for their own reproduction [6] as they are carried through the mesenteric lymph nodes to the thoracic duct and the lymphatics and then through to the reticuloendothelial tissues of the liver, spleen, bone marrow, and lymph nodes. Once there, they pause and continue to multiply until some critical density is reached. Afterward, the bacteria induce macrophage apoptosis, breaking out into the bloodstream to invade the rest of the body. [4]

The bacteria then infect the gallbladder via either bacteremia or direct extension of infected bile. The result is that the organism re-enters the gastrointestinal tract in the bile and reinfects Peyer patches. Bacteria that do not reinfect the host are typically shed in the stool and are then available to infect other hosts. [2, 4] See the image below.

Life cycle of Salmonella typhi. Life cycle of Salmonella typhi.

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