After uptake by macrophages, Salmonella is delivered to which structure first?

• A. Spleen
• B. Liver
• C. Lymph nodes
• D. Blood

Answer: (C)

After Salmonella is taken up by macrophages in the gut-associated lymphoid tissue, these infected cells travel via the lymphatic system rather than directly entering the bloodstream. The first structure they reach is the draining lymph nodes, especially the mesenteric lymph nodes that receive lymph from the intestinal mucosa. There, Salmonella can establish a foothold and begin disseminating, before spilling into the bloodstream to reach other organs. The spleen and liver are later sites reached once the bacteria are in circulation, making them secondary targets rather than the initial destination. Blood is the route for systemic spread, but the very first stop after macrophage uptake is the lymph nodes.