Intracellular destruction of salmonellae in genetically resistant mice.

Virulent Salmonella typhimurium, 2000 LD50, were injected intraperito-neally into inbred male A/J mice, genetically resistant to salmonella infection. Peritoneal exudate cells were harvested between 5 and 54 h after infection and examined by electronmicroscopy. Polymorphs were seen ingesting as well as digesting the pathogens as early as 5 h after infection. Macrophages were equally active in destroying the phagocytosed organisms throughout this period. In the meantime, the proliferation of salmonellae appeared to occur extracellularly in the peritoneal cavity as evidenced by their division.