Interactions between macrophages of guinea pigs and Salmonellae. I. Fate of Salmonella typhimurium within macrophages of normal guinea pigs.

A suspended cell culture procedure was described for the cultivation of guinea pig macrophages infected with Salmonella typhimurium. The fate of the intracellular bacteria was assessed by quantitative recovery of viable bacteria with 0.5% solution of sodium desoxycholate. Two strains of S. typhimurium with different degrees of virulence for mice were compared. There was an initial destruction of intracellular bacteria of both strains; however, the extent of this destruction differed. Approximately 1% of the avirulent bacteria initially phagocytized survived at the end of 4 hr, whereas approximately 8% of the virulent bacteria survived at the end of 3 hr. After this initial killing, the intracellular bacteria began to multiply at a logarithmic rate between 3 and 21 hr after phagocytosis, and then a stationary phase was attained. The rate of this multiplication was comparable for both strains.