Salmonella typhi does not inhibit phagosome-lysosome fusion in human monocyte-derived macrophages.

We examined phagosome-lysosome fusion in Salmonella typhi-infected human monocyte-derived macrophages and its relevance to the intracellular survival of this bacterium in vitro. S. typhi was found to survive and multiply in human monocyte-derived macrophages, whereas S. typhimurium was killed easily, indicating that the survival of Salmonella serovars is host-specific. Neither S. typhi nor S. typhimurium inhibited phagosome-lysosome fusion in human monocyte-derived macrophages. No difference between the phagosome-lysosome fusibilities of freshly prepared human monocytes and monocyte-derived macrophages was observed. These results suggest that S. typhi may survive by adapting to the conditions within fused phagolysosomes of human monocyte-derived macrophages.