The number of bacteria isolated from various tissues. CFUs from blood, heart, kidneys, and joints were determined from mice infected with either Map^–SA (open squares) or Map⁺SA (filled squares) at various times after infection. Data are expressed as the mean CFU ± SE of the mean of 4 mice/group at each time point. There was no statistical differences between infection groups at any of the time points examined (Student t test). *The bacterial density in the joints harvested from Map^–SA–infected mice 4 days after infection was 5,750 ± 2,453.