FIGURE 1.

Colonization and invasion rates of three Salmonella Typhimurium strains in four human cell lines. LS174T, Caco-2, HeLa, and THP-1 cells were infected with S. Typhimurium SL1344, ΔyqiC, and ΔyqiC′. The CFUs in output pools A and B represent the colonized and intracellular bacteria, respectively. The CFUs of the cell lysates containing bacteria were counted, and the bacterial counts of the colonizing and invading S. Typhimurium ΔyqiC and ΔyqiC′ CFUs were compared with those of the colonizing and invading S. Typhimurium SL1344 using the Student’s t-test. ^∗∗∗p < 0.001.