Figure 5.

Bacterial load in blood and organs after intravenous infection of pigs with strain 10 and mutant derivatives (a) 10∆penA, (b) 10∆SSU1869, and (c) 10∆SSU1940. Cells of strain 10 and mutant derivatives carrying a spectinomycin-resistance marker, were mixed 1:1 and the resulting suspensions were used to infect animals. Bacterial loads of the wildtype and mutants in blood, one- and two-day post-infection (dpi), in internal organs and brain, four dpi, were determined by plating on solid media containing or not spectinomycin and counting colony-forming units after overnight incubation. The ratio wild type/mutant is shown and the number of animals that resulted positive for each strain is depicted at the top. The ratio wildtype/mutant in blood remained similar to the three dpi.